Diagnostics of faults in vehicle components and systems (Audi A3 8L)

Description of diagnostics of electronic control systems and diagnostic codes are given in the section Engine electrical systems.

This Section offers the simplest scheme for identifying the causes of malfunctions and failures occurring in vehicle units and systems. Failures and their possible causes are divided into groups according to their relationship to specific components or systems of the vehicle, such as the engine, cooling system, etc. In addition, the text provides links to Sections and Subsections related to these problems.

Remember that successfully completing a troubleshooting is not a black art reserved for experienced professional mechanics, but a combination of knowledge and a patient, systematic approach to investigating the problem. Always move from simple to complex, take each check to its logical conclusion, and try not to miss the obvious – anyone can forget to fill the fuel tank or leave the lights on overnight.

Finally, you should always try to get a clear picture of the progression of the fault and take appropriate steps to prevent a recurrence. If the electrical equipment failure occurred due to a poor contact quality, check the condition of all other contacts and electrical connectors in the system at the same time. If the same fuse continues to blow several times in a row, there is no point in replacing it further - you should try to find out the cause of the failure. Remember that the failure of a minor component may be a sign of a malfunction of a more important unit or the entire system.

Engine

If the engine does not start, you should analyze the situation. For the engine to start at all, two basic conditions must be met. The fuel-air mixture must enter the cylinders, and a spark must be generated at the spark plug. Therefore, first, you should check whether fuel is being supplied. How to proceed in this case is described in the section Fuel and exhaust systems.

To determine whether a spark is being generated, remove all the spark plugs, insert them into the tips and apply them individually to ground. Note: To avoid damaging the catalytic converter, gasoline injection should be excluded. To do this, disconnect the plug connection of the injectors. If there is no spark, determine the fault according to section Engine electrical systems.

Warning: Observe safety precautions when working with the electronic ignition system (section Engine electrical systems).

Do not hold the tip or ignition cable with your hands, but use well-insulated pliers. Ask an assistant to start the engine. If the spark does not slip, determine the malfunction using the section Engine electrical systems.

The engine does not turn over when trying to start it

1. There is corrosion of the battery terminals or the fastening of the wire tips on them has become loose. Check the condition of the terminals and tips. Tighten the terminal clamps, remove traces of corrosion if necessary.

2. The battery is discharged or defective. If the cable ends are found to be clean and securely connected to the battery terminals, turn the ignition switch to the ON position, then turn on the headlights and/or windshield wipers. If these electrical equipment do not function, the battery is discharged.



3. The transmission is not correctly set to the "P" position (automatic) or to neutral gear (manual transmission), or the clutch is not fully depressed.

4. The wiring in the starting system circuit is broken or the wires are loose on the terminals. Check if there is at least 10 V at terminal 50 of the traction relay when the engine is started, which is necessary for retraction. Check the condition of the wires, terminals and electrical connectors of the battery, the starter traction relay and the ignition switch.

5. The starter pinion is jammed in the flywheel ring gear. On models equipped with a manual transmission, set it to gear and, pushing the car by hand, turn the engine over. Remove the starter at the first opportunity and check the condition of the pinion and flywheel ring gear.

6. The starter traction relay is faulty (section Engine electrical systems).

7. The starter is faulty (section Engine electrical systems).

8. The ignition switch is faulty.

The engine turns over but does not start

1. The launch is not performed correctly

The order of starting a gasoline engine:

Set the parking brake, depress the clutch pedal. On automatic transmission models, press and hold the brake pedal. On automatic transmission, place the selector in the "P" or "N" position. Do not apply gas. Turn the ignition key and hold it until the engine starts. If the engine does not start within 20 seconds or stops immediately, repeat the starting process with the gas pedal half-pressed. As soon as the engine starts, release the ignition key.



In frost below -15°C and at an altitude of more than 1000 m above sea level: Start for at least 10 s with the pedal half-pressed.

Be sure to start moving immediately. If there is severe frost, let the engine run for 30 seconds.

If the engine does not start after 10 seconds, interrupt the start and try again after half a minute.

Warning: Several unsuccessful starting attempts in a row can damage the catalytic converter because unburned fuel combusts explosively when heated in the catalytic converter.

Only on a hot engine after starting, add a little gas.

2. The engine immobilizer is faulty.

3. The fuse is faulty:

• electric fuel pump;
• electronic injection system.

For checking fuses, please refer to the subsection Fuses.

4. The fuel tank is empty or poor quality fuel has been added.

5. The air filter is heavily contaminated. There are vacuum leaks in the air supply elements, malfunctions in the fuel injection and ignition control systems.

6. The battery is discharged (the engine turns over too slowly). Check the functioning of electrical equipment.

7. The battery terminal connections are corroded or loose (refer to the previous Section).

8. The fuel pump is faulty.

9. Damaged or excessively wet ignition system components (Section Engine electrical systems).

10. Spark plugs are worn or faulty, or the gap is set incorrectly (Section Engine electrical systems).

11. The wiring of the electrical circuit of the starting system is broken or disconnected, or the fastening of the wires at the terminals is loose.



12. The ignition coil circuit wiring is broken or disconnected, or the wires are loose at the coil terminals (Section Engine electrical systems).

13. Compression pressure too low. Replace cylinder head gasket. Repair engine if necessary.

Diesel engine:

14. The launch was performed incorrectly

Starting procedure for a turbodiesel engine:

On a cold engine and at an outside temperature below +8°C, apply the parking brake and depress the clutch pedal. On AT, set the selector to position "P" or "N" - manual transmission. Turn the ignition key to position II and wait until the pre-glow indicator lamp goes out. Immediately after the indicator lamp goes out, start the engine without giving gas. If irregular flashes appear, do not turn off the starter until the engine runs smoothly (no more than 30 sec). If the engine does not start, try starting again after half a minute, as described above. During the preheating process, do not turn on the current consumers (light, heated rear window).

On a cold engine and at an outside temperature above +8°C, as well as on a warm engine, preheating is not required. The engine can be started immediately. Do not give gas.

15. The engine immobilizer is faulty.

16. The fuse is faulty:

• electric fuel pump;
• preheating systems.

17. The engine is not warmed up: check the proper functioning of the pre-heating device.

18. There is no voltage on the electromagnetic shut-off valve. Connect a voltmeter or LED tester to the switch. Turn on the ignition. The LED should light up. Otherwise, you need to find the break in the wiring and fix it.



19. The electromagnetic shut-off valve is faulty. Check the reliability of the electromagnetic switch fastening, check the contacts. Turn the ignition on and off. A click should be heard in the switch.

20. There is damage in the fuel supply line or air in the lines:

• a) The lines or hoses are mechanically damaged or clogged. Clean the fuel lines and bleed air from the lines and filter.
• b) The fuel filter is clogged. Replace the filter element.
• c) In winter, check the filter and lines for ice or wax. Park the car in a heated garage, add gasoline to the system.
• d) The tank ventilation or fuel intake mesh filter is clogged.

Clean it out.

21. The fuel injection start adjustment is out of adjustment. Check and make adjustments.

22. The injectors are faulty. Check. Loosen the union nuts one by one – when you loosen the nut of the faulty cylinder, the engine speed will not drop.

23. The high-pressure fuel pump (HPFP) is faulty. Install a new or known good HPFP for testing.

24. Compression pressure too low. Replace cylinder head gasket. Repair engine if necessary.

The starter operates without turning the engine

1. The starter pinion is jammed. Remove the starter (Chapter Engine electrical systems) and check its condition.

2. The starter gear teeth or flywheel ring gear are worn or damaged.

Difficulty starting a cold engine

1. The battery is discharged or not sufficiently charged.

2. There is a malfunction in the power supply system components or electrical equipment.

3. Paraffin in fine filter of diesel engine. Replace filter element. Fill with winter fuel or dilute with gasoline



4. The glow plugs of the diesel engine are faulty.

Difficulty starting a hot engine

1. The air filter is blocked

2. There is a malfunction of the power supply system components or electrical equipment

3. Fuel does not reach the injection system injectors

4. The fuel injection advance angle of the diesel engine has been lost.

5. Low compression in the cylinders, faulty or out of adjustment fuel injection pump of the diesel engine.

The starter engages too noisily or with difficulty

1. The starter gear teeth or flywheel ring gear are worn or damaged.

2. The starter mounting bolts are missing or their tightening force has weakened.

The engine starts but immediately stalls

1. The engine immobilizer is faulty.

2. The electrical wiring is faulty or the wires on the coil or generator terminals are loose.

3. There is a malfunction of the power supply system components or electrical equipment

4. The basic settings of the electronic control unit (ECM) have been violated.

5. Damage to the exhaust system/catalytic converter.

6. There are vacuum losses through the gasket surfaces of the intake manifold or fuel injection unit. Make sure that the fastening bolts/nuts are tightened securely, check the fact and quality of fastening on their fittings on the intake manifold of all vacuum hoses. Check the condition of the hoses and their correct connection (specifically to your fittings).

The stability of the engine at idle speed is impaired

1. There is a loss of vacuum. Make sure that the fastening bolts/nuts are tight, check the fact and quality of fastening on their nipples on the intake manifold of all vacuum hoses. Listen to the running engine with a stethoscope or a section of fuel hose. The presence of a hissing sound will help to identify the source of the vacuum "leak". A solution of soapy water can be used for checking no less effectively.



2. There is a malfunction of the power supply system components or electrical equipment

3. The crankcase ventilation system valve is blocked

4. The air filter is blocked

5. The fuel pump does not supply sufficient fuel to the injection system injectors

6. There are leaks through the cylinder head gasket. Measure the compression pressure in the engine cylinders.

7. The working projections of the camshaft cams are worn out

Diesel engine:

8. The quality of the fuel hose connections on the high-pressure fuel pump and fuel filter is damaged. Replace the fuel hoses, secure them with clamps, tighten the screws of the angular connections.

9. The fuel injection pump mount is mechanically damaged or loose. Check the mount.

10. The connections of the return line and the fuel supply line are reversed. Put the connections back in place. The screw for connecting the return line is marked "OUT".

11. There is damage in the fuel supply line:

• a) The pipes or hoses are mechanically damaged or clogged. Clean the fuel pipes.
• b) The fuel filter is clogged. Replace the filter element.
• c) In winter, check the filter and lines for ice or wax. Park the car in a heated garage, add gasoline to the system.
• d) The tank ventilation or fuel intake mesh filter is clogged.

Clean it out.

12. The fuel injection start adjustment is out of adjustment. Check and make adjustments.

13. The injectors are faulty. Check. Loosen the union nuts one by one – when you loosen the nut of the faulty cylinder, the engine speed will not drop.

14. The high-pressure fuel pump (HPFP) is faulty. Install a new or known good HPFP for testing.

There are misfires when the engine is idling

1. Spark plugs are worn or dirty, or the gap is incorrectly set (Section Engine electrical systems).

2. There is a malfunction of the power supply system components or electrical equipment

3. Spark plug wires are faulty (Section Engine electrical systems).

4. Low-quality fuel was added. The fuel filter is clogged.

5. There are losses of vacuum in the intake manifold or through hose connections

6. Insufficient or unevenly distributed compression pressure in the cylinders. Perform a compression test

7. There are problems with the engine management system.

There are misfires when the car is moving in gear

1. The fuel filter is blocked or the fuel system is contaminated

2. The spark plugs are faulty, dirty, or the gap is set incorrectly (Section Engine electrical systems).

3. There is a malfunction in the power supply system components or electrical equipment.

4. There is a defect in the spark plug wires (Section Engine electrical systems).

5. Components of the exhaust gas toxicity reduction systems are faulty.

6. Insufficient or uneven distribution of compression pressure between cylinders. Remove spark plugs and measure compression pressure

7. The ignition system is faulty (Section Engine electrical systems).

8. There are vacuum losses at the throttle body, intake manifold or through vacuum hoses

The engine stalls

1. Idle speed adjustment is out of order.

2. The fuel filter is blocked and/or moisture or dirt has entered the fuel system

3. There is a failure of power supply components or sensors

4. Components of the exhaust gas toxicity reduction systems are faulty.

5. The spark plugs are faulty, dirty, or the gap is set incorrectly. Also check the condition of the spark plug wires (Section Engine electrical systems).

6. There are losses of vacuum at the throttle body or through the vacuum hoses

The engine does not develop full power

1. There is a malfunction of the power supply system components or electrical equipment (Section Engine electrical systems).

2. The air cleaner is clogged. Clean or replace.

3. Spark plugs are faulty or the spark plug gap is set incorrectly

4. The ignition coil is faulty (Section Engine electrical systems).

5. AT fluid level does not meet requirements

6. The clutch is slipping

7. The fuel filter is blocked and/or dirt/moisture has entered the fuel system

8. The wrong grade of fuel has been added. Fill the tank with fuel of the required octane rating.

9. The turbocharger control valve is damaged.

10. The camshaft phase shift activator is faulty.

11. Insufficient or uneven compression pressure across cylinders. Perform a compression test, the results of which can reveal valve leaks and/or a leaky cylinder head gasket

Additional for diesel engine

12. The air cleaner is clogged. Clean or replace.

13. Uneven fuel supply from the high-pressure fuel pump to the cylinders. Adjust on a warm engine.

14. The moment of start of fuel supply of the high-pressure fuel pump is set incorrectly. Set it.

15. The fuel filter or high-pressure fuel pump (injector) is clogged. Wash the pre-filter, change the fine filter element, clean the spray nozzle or replace the pump (injector).

16. The maximum crankshaft speed adjustment is out of adjustment.

There are pops in the intake system or shots in the exhaust system

1. There is a malfunction of the power supply system components or electrical equipment (Section Engine electrical systems).

2. There is a defect in the secondary circuit of the ignition system (destruction of spark plug insulators or defects in spark plug wires) (Chapter Engine electrical systems).

3. The fuel injection system needs adjustment or its components are excessively worn

4. There are vacuum losses at the throttle body, intake manifold or through vacuum hoses

5. The valves are stuck

6. The order of connecting the spark plug wires is violated (Section Engine electrical systems).

When accelerating or driving uphill, detonation sounds occur

1. Low quality fuel was used.

2. There is a malfunction of the power supply system components or electrical equipment (Section Engine electrical systems).

3. The wrong type of spark plugs are installed. Check the plugs and coils for damage (Section Engine electrical systems).

4. The basic settings of the electronic control unit have been violated.

5. The knock sensor is faulty.

6. There are losses of vacuum

Pre-ignition takes place (the engine continues to run after the ignition is turned off)

1. Idle speed is too high.

2. There is a malfunction of the power supply system components or electrical equipment (Section Engine electrical systems).

3. The purge valve of the fuel vapor capture system (EVAP) adsorber is damaged.

4. Engine operating temperature is excessive. Possible causes of this problem may be low coolant levels, thermostat failure, radiator blockage, or a faulty water pump.

Diesel engine smokes

1. Black smoke:

• a) The air cleaner is dirty. Flush and fill with fresh oil or replace the element.
• b) Incorrect fuel used. Flush tank and change fuel.
• c) The moment of start of injection of the high-pressure fuel pump is set incorrectly.

2. Blue smoke:

• a) Oil burning in the combustion chamber due to worn piston rings, high oil level in the air cleaner, worn seals in the turbocharger covers, leaks in the gasket between the crankcase and the turbocharger. Repair the engine, set the normal oil level, replace the seals, tighten the turbocharger mounting bolts or replace the gasket.
• b) No fuel is supplied to one of the injectors. Check by heating the outlet pipes of the manifold.
• c) Poor fuel atomization by the injector due to a faulty valve or a broken atomizer. Grind the valve or replace the injector.

3. White or brown smoke:

• a) Low temperature in the cooling system. Check the thermostat.
• b) Poor operation of the injectors due to wear or breakage of the atomizer. Replace the atomizer.

Engine electrical equipment

The battery does not hold a charge

1. The alternator drive belt is worn or damaged, or its tension adjustment is incorrect (Section Engine electrical systems).

2. The electrolyte level is insufficient or the battery is very discharged (Section Engine electrical systems).

3. There is corrosion of the battery terminals or the fastening of the wire tips to them has become loose (Section Engine electrical systems).

4. The generator does not provide the required charging current (Section Engine electrical systems).

5. The charging circuit wiring is broken or otherwise damaged, or the wires are loose at the terminals

6. A short circuit in the wiring creates a constant leakage of current generated by the battery to ground

7. There is an internal battery defect.

The ignition indicator lamp does not go out when the revs increase

1. The drive belt is loose. Check the V-belt tensioner.

2. Damage to the overrunning clutch (turbodiesel only). Remove the generator and turn the generator drive shaft to the left. If the working surface of the pulley does not rotate, then the damage is usually in the overrunning clutch.

3. Voltage regulator/generator faulty. Disconnect the (D+) wire from the back of the generator and turn on the ignition. If the test lamp does not light now, the fault is usually in the voltage regulator or generator.

4. Brush wear. Visually inspect the brushes, replace if necessary.

5. Regulator damaged. Check and replace if necessary.

6. Generator damage. Check and replace if necessary.

7. Damage to the wire between the generator and the voltage regulator. Disconnect the blue wire at contact 12 of the T32a plug connection and at the instrument panel unit. If the indicator lamp does not light now, the D+ wire is connected to ground. Replace the harness.

8. Damage to the instrument panel unit. If, after disconnecting the blue wire from the T32a plug connection with the ignition on, the indicator lamp lights up, the fault is usually in the instrument panel unit.

The ignition indicator lamp does not light when the ignition key is turned to the "ON" position (when the ignition is turned on)

1. The control lamp on the instrument panel has burned out or otherwise failed.

2. The generator is faulty.

3. There is a defect in the printed circuit board, wiring inside the instrument cluster or lamp socket

The charge indicator lamp lights up after the ignition is turned off

Positive diodes are short-circuited. Check diodes, replace diode board.

Starter

If the starter does not turn, first check that the required voltage of at least 10 V is present at terminal 50 of the traction relay. If the voltage is lower than this value, check the wires included in the starter current circuit according to the diagram.

You can check whether the starter operates at full battery voltage as follows:

• without shifting into gear, turn on the ignition.
• jumper terminals 30 and 50 of the starter with a wire of at least 4 mm² cross-section, also refer to the section "Checking the traction relay".

If the starter works perfectly, the cause of the malfunction should be sought in the wires to the starter. If the starter does not work, it should be checked in the removed state.

Verification condition: At the connection points, the wires must be well secured and must not be oxidized.

The starter does not turn when the ignition switch is turned on

1. The battery is discharged. Charge the battery.

2. Jumper terminals 30 and 50 of the starter: The starter rotates. Wire 50 to the ignition switch is broken, the starter switch is faulty. Fix the break, replace the defective parts.

3. Ground cable or connector broken, battery discharged. Check battery cables and connectors, measure battery voltage, charge if necessary.

4. Insufficient current flow due to loose or oxidized connectors. Clean battery terminals and poles, check connections between battery, starter and ground.

5. No voltage at terminal 50 of the traction relay. Wire break, starter switch faulty.

The starter rotates slowly and does not turn the crankshaft

1. Low battery. Charge the battery.

2. Summer oil is filled. Fill with all-season oil.

3. Insufficient current flow due to loose or oxidized connectors. Clean battery terminals and poles, check connections between battery, starter and ground.

4. Carbon brushes do not fit the commutator, are stuck in the guides, are worn, broken, oily or dirty. Check the brushes, clean or replace. Check the guides.

5. Insufficient distance between brushes and commutator. Replace brushes and clean brush guides.

6. The commutator is grooved or burnt and oiled. Treat the commutator or replace the anchor.

7. No voltage at terminal 50 (min. 8 V). Check starter switch or solenoid relay.

8. The bearing is broken. Check the bearing, replace if necessary.

9. The traction relay is faulty. Replace the traction relay.

The starter catches and turns the engine jerkily

1. The pinion drive is faulty. Replace the pinion drive.

2. The gear is dirty. Clean the gear.

3. The flywheel ring gear is faulty. Treat the ring gear, replace the flywheel if necessary.

The starter pinion does not move away from the ring gear

1. The pinion drive or threads are dirty or damaged. Clean or replace the pinion drive.

2. The traction relay is faulty. Replace the traction relay.

3. The return spring is weak or broken. Replace the return spring.

The starter continues to operate after the ignition key is released

1. The traction relay is stuck and won't turn off. Turn off the ignition immediately and replace the traction relay.

2. The ignition switch does not turn off. Disconnect the battery immediately, replace the ignition switch.

Power supply system

Excessive fuel consumption

1. The air filter element is dirty or blocked.

2. There is a malfunction in the power supply system components, electrical equipment or electronic control

3. Leaks in the air intake system.

4. Damage to the exhaust system/catalytic converter.

5. Insufficient tire pressure or incorrect size tires installed.

Diesel engine

6. Clogged return line. Blow air through the return line from the injection pump to the fuel tank.

7. Idle speed and maximum speed are too high. Adjust.

8. The engine has mechanical damage. Check the compression, repair the engine if necessary.

There are fuel leaks and/or a smell of gasoline

1. There are leaks in the fuel supply lines or vent lines

2. The fuel tank is full. Refuel only until the gun automatically switches off.

3. There are leaks or evaporations from the fuel system lines and a decrease in exhaust toxicity.

The engine does not start

1. When the starter is turned on, the electric fuel pump does not work (no noise from work can be heard). Lightly tap the pump body to release the jammed part. Check if voltage is applied to the pump. Check the fuse for proper operation. Check the electrical contacts for good conductivity.

2. The fuel pump relay is faulty. Check the relay.

3. The injector valves are stuck. Check the injectors, replace if necessary. Check the voltage supply to the injectors. To do this, disconnect the injector connector. Connect the diode test lamp to the wire and turn on the starter. The test lamp should blink.

4. There is no signal from the ignition timing sensors or engine speed sensor. Check the electrical wiring. Perform a fault memory query.

5. Fuel lines are damaged, clogged or leaky, hoses are defective.

6. The fuel filter is clogged.

7. Presence of ice or wax in the filter or diesel engine lines.

8. The fuel tank ventilation is clogged, the filter in the tank is clogged.

9. The diesel engine injectors are damaged. Loosen the union nuts one by one and check if the corresponding cylinder works.

Cold engine starts poorly, runs unsteadily

1. CO content does not meet requirements. Check CO content and idle speed.

2. Temperature sensor is faulty. Check coolant/intake air temperature sensor.

3. The fuel pressure does not correspond to the required value. Check the fuel pressure.

A warm engine starts poorly and runs unsteadily

1. The air intake system is leaky. Check the intake system. To do this, leave the engine idling and cover the seals and connections on the intake tract with gasoline. If the RPM increases briefly, eliminate the leaky areas.

Warning: Gasoline vapors are poisonous, do not inhale them.

The engine runs intermittently

1. Electrical connections to the fuel pump are intermittently interrupted. Check the condition of the plug connections and connectors of the electrical wires of the fuel pump, air flow meter and fuel pump relay. Check the fuse and contact locations on the fuel pump relay. Clean the contacts, replace if necessary.

2. Low fuel quality, vapor lock formation. Fill with quality fuel.

3. Fuel delivery volume too low. Check pump performance.

4. The fuel filter is faulty. Replace the fuel filter.

5. The fuel pump is faulty. Check the fuel pump.

6. The injectors are faulty. Check the injectors.

7. The throttle position sensor is faulty. Check the throttle position sensor.

8. Weak connection of fuel hoses to the high-pressure fuel pump and fuel filter of a diesel engine.

The engine operates intermittently in transient and idle modes

1. The air intake system is leaky. Check the connections of the intake system. Start the engine and lubricate the contact points and connections in the intake tract with gasoline. If the engine speed increases briefly, eliminate the leak.

2. Incorrect idle speed adjustment. Check the idle speed control valve, throttle position sensor, lambda adjustment.

3. The full load sensor is faulty or incorrectly adjusted. Check the throttle position sensor.

Hot engine won't start

1. Incorrect CO content adjustment. Check CO content and idle speed.

2. Too high pressure in the fuel system. Check the fuel pressure, replace the pressure regulator if necessary.

3. The return line between the pressure regulator and the fuel tank is clogged or kinked. Clean or replace the line.

4. The engine temperature sensor is faulty. Check the temperature sensor.

5. Fuel system is leaking. Visually inspect all connections in the engine and electric fuel pump area. Tighten all connections.

6. The air intake system is leaking. Check all connections of the intake system.

The engine runs after being turned off

1. Injectors are leaking. Check injectors.

2. The fuel shut-off valve on the diesel engine does not work.

Lubrication system

The control lamp does not light after the ignition is turned on

1. The oil pressure sensor is faulty. Turn on the ignition, disconnect the wire from the oil pressure sensor and short it to ground. If the lamp lights up, replace the sensor.

2. There is no voltage supplied to the sensor, the contacts are corroded. Check the electrical wires and contacts.

3. The indicator lamp is faulty. Replace the indicator lamp.

4. The control unit is faulty. Replace the control unit.

The indicator light does not go out after starting the engine

The oil is overheated. If the indicator lamp goes out after gas is supplied, nothing needs to be done.

The indicator light does not go out after gas is supplied or lights up while driving

1. Oil pressure is too low. Check oil level, top up if necessary. Check oil pressure.

2. The wire to the oil pressure sensor has a short circuit to ground. Disconnect the cable from the sensor and move it to the side (without shorting to ground), turn on the ignition. If the lamp lights up, check the wire.

3. The oil pressure sensor is faulty. Replace the sensor.

Oil pressure too low at all speeds

1. There is too little oil in the engine. Add oil.

2. The mesh filter is clogged. Remove the oil pan, clean the mesh filter.

3. The oil pump is worn out. Remove the oil pump and check it, replace it if necessary.

4. Bearing damage. Remove the engine.

Too low oil pressure at low speeds

The pressure reducing valve is stuck open due to contamination. Remove and check the valve.

Oil pressure too high at speeds above 2000 rpm

The pressure reducing valve does not open due to contamination. Remove and check the valve.

Cooling system

Overheat

1. Not enough coolant in the system

2. The water pump drive belt is worn or damaged, or its tension is not adjusted correctly

3. The internal radiator channels are blocked or the radiator grille is dirty (obstructed)

4. Thermostat is faulty.

5. Fan blades are broken or cracked

6. The viscous fan clutch is faulty. Check the fan clutch: Increase the engine speed when it is warm. As soon as the fluid temperature reaches 90 – 95°C, the fan speed will increase, which will be noticeable by ear.

7. The coolant temperature gauge is faulty. Check the sensor.

8. The coolant pump is faulty. Remove and check the pump.

9. The radiator cap does not hold pressure. Perform a pressure test of the cap (contact a service station).

Hypothermia

1. Thermostat is faulty

2. The temperature meter readings are inaccurate.

External coolant leaks

1. The hoses are damaged or destroyed as a result of aging of the material or their fastening on the fittings has become loose. Replace the hoses and/or tighten the clamps of their fastening

2. The water pump seals are damaged. In this case, the coolant will leak through the inspection hole in the pump body

3. There are leaks from the internal channels of the radiator or side tank. Professional radiator repair is required

4. There are leaks through the engine drain plug or squeeze plugs of water galleries

Internal coolant leaks

Warning: Internal coolant leaks are usually detected by checking the engine oil condition. Inspect the dipstick blade and the inside surfaces of the cylinder head(s) for traces of water and oil foaming.

1. There are leaks through the cylinder head gasket. Perform a pressure test of the cooling system.

2. There are cracks in the cylinder walls or in the head casting. Disassemble the engine to check

Coolant losses occur

1. There is too much coolant in the system

2. The coolant boils away as a result of engine overheating

3. There are internal or external coolant leaks

4. The radiator cap is faulty. Check the cap with pressure.

Coolant circulation is disrupted

1. The water pump is not functioning properly. The easiest way to check that the pump is functioning is to pinch the upper radiator hose while the engine is idling. If you feel a jolt of fluid inside the hose when you release it, the pump is functioning properly

2. The cooling system is clogged. Drain the coolant, flush the system and fill it with fresh mixture. If necessary, remove the radiator and perform a reverse flow flush.

3. The water pump drive belt is worn or damaged, or its tension is not adjusted correctly

4. Thermostat is stuck.

Heater

The heater fan does not work

1. The fan motor fuse is faulty. Check the fan fuse and replace if necessary.

2. The fan switch is faulty. Check if voltage is applied to the pre-resistors, remove and check the fan switch.

3. The electric motor is faulty. Check if voltage is applied to the fan motor contacts with the ignition on and the fan switch closed. If voltage is applied, replace the motor.

The heater fan does not work at one of the stages

Pre-resistor is faulty. Replace the connection board.

The heater does not turn off with the regulator

1. The switch is faulty. Check the switch.

2. The control mixing flap cables are damaged or do not move well. Replace the cables.

Heating power too low

1. Coolant level too low. Check coolant level, top up if necessary.

2. The heater control unit has a heavy movement, is faulty. Check the heater control unit, replace the cable if necessary.

Noise in the area of the heater fan

1. Dirt and leaves got in. Remove the fan and clean it, clean the air duct.

2. Impeller imbalance, bearing failure. Remove the fan motor, check for ease of movement.

Clutch

The clutch does not disengage (the manual transmission control lever does not move freely into reverse gear and back when the clutch pedal is pressed to the floor)

The clutch disc is bent or damaged

The clutch is slipping (engine speed increases without increasing vehicle speed).

1. The clutch disc is contaminated with oil or its friction linings are worn. Remove the clutch and check the condition of its components.

2. The clutch disc has not been properly run in. It may take 30 to 40 normal car starts to fully run in a new disc.

3. The pressure plate/clutch basket is worn out.

There is a strong vibration when the clutch is engaged

1. The clutch disc is oily. Remove the clutch and check the condition of its components. Eliminate any leaks found.

2. The splines of the driven disk hub are worn out (clutch disc). Remove the clutch and check the condition of its components.

3. The pressure plate/clutch basket or flywheel is bent. Remove the clutch and check the condition of its components and the flywheel.

Jerks when engaging the clutch

1. Damage to engine and gearbox mounts. Check and replace if necessary.

2. The gearbox mount in the suspension is loose. Tighten the mounting bolts.

3. Uneven pressure plate contact. Replace clutch basket.

4. The crankshaft is not aligned with the gearbox. Check the alignment.

A squealing or rattling noise occurs when the clutch is fully engaged (pedal released)

The clutch release bearing is seized. Remove the clutch and inspect the bearing. Remove any burrs and burrs, and lubricate the bearing before reinstalling.

A squealing or rattling noise occurs when the clutch is fully disengaged (the pedal is pressed)

1. The release bearing is worn or damaged

2. Worn or damaged springs (or aperture blades) pressure plate in the clutch basket

The clutch pedal remains depressed to the floor after it is released

The piston of the clutch master or slave cylinder is jammed. Damage to the clutch hydraulic system or release bearing. Check the condition, remove the clutch components if necessary.

Manual transmission (MT)

When the gearbox is in neutral, extraneous noises occur while the engine is running

1. The input shaft bearing is worn out.

2. The bearing of the driven shaft pinion is damaged.

3. The intermediate shaft bearings are worn out.

4. The intermediate shaft axial play adjustment washers are worn or damaged.

Extraneous noises occur in any position of the manual transmission

1. Any of the above reasons and/or:

2. There is not enough transmission oil in the manual transmission (his level dropped).

Extraneous noises occur in a particular gear

1. The gear teeth of this transmission are worn, damaged or chipped.

2. The synchronizer of this gear is worn or damaged.

The gearbox "jumps" out of the highest gear

Dirt has gotten between the gearbox housing and the engine, or the gearbox has shifted relative to the engine.

Difficulties occur when shifting gears

1. The clutch is not fully depressed (disengaged).

2. the shift rod is damaged, loosened or out of adjustment. Carefully check the condition of the components and replace any defective ones if necessary.

There are transmission oil leaks

1. There is too much transmission oil in the gearbox. Drain the excess if necessary.

2. The differential seals need to be replaced.

Automatic transmission (AT)

Warning: Due to the complexity of the AT design, full diagnostics of its faults and repair of components are beyond the skills of the average amateur mechanic. If any problems with the operation of the AT other than those listed below occur, the car should be taken to a car service workshop or representative office of AUDI A3 for inspection and repair.

Common problems associated with the operation of the switching mechanism

The following can be attributed to failures associated with a malfunction of the shift rod adjustment:

• a) The engine can be started in transmission positions other than "P" (Park) and "N" (Neutral).
• b) The transmission position indicator readings differ from the actual gear selected.
• c) The vehicle is moving with the transmission in position "P".

Adjust the gear shift rod

The transmission slips, shifts with difficulty, makes strange noises, or does not allow the vehicle to move when shifted into one of the forward or reverse gears.

1. There are many possible causes for the problems listed in the title, but only one of them falls within the competence of the amateur mechanic - incorrect transmission fluid level.

2. Before taking your car to a car service center, check the level and condition of the transmission fluid (Chapter 1). Adjust the level according to the requirements of the Specifications or change the fluid together with the filter. If the situation does not improve, seek help from specialists.

There are transmission fluid leaks

1. AT fluid is dark red in color. Its leaks should not be confused with engine oil, which can be carried to the transmission housing by the oncoming air flow.

2. To identify and locate the source of the leak, first remove all traces of dirt and grease from the transmission housing. Use a suitable degreaser and/or steam clean. Then take the vehicle for a short drive at low speed (so that traces of a leak are not carried away by the oncoming flow far from its source). Stop, jack up the car and visually inspect to determine the source of the leak. Most often, these are:

• a) Transmission oil pan: Tighten the mounting bolts and/or replace the oil pan gasket.
• b) Fluid filler tube: Replace the rubber seal where the tube enters the transmission case.
• c) Transmission fluid lines: Tighten fittings or replace lines.
• d) Vent Tube: Transmission is overfilled and/or water has entered the transmission.

Bridges

Extraneous noises

1. Normal road noise. Cannot be adjusted.

2. Tire noise. Check the condition of the treads and the inflation pressure of the tires.

3. Wheel bearings are worn or damaged, or their tightening force has weakened.

Vibrations

Check the condition of the wheel bearings by jacking up the appropriate corner of the car one by one and rotating the wheel manually. Listen to the sounds coming from the bearing. Remove the bearings and check their condition.

Oil leaks

The drive shaft seals are damaged.

Brake system

Warning: Before making a final determination that there is a problem with the brake system, make sure that the tires are in good condition and inflated to the correct pressure, that the front wheel alignment is correct, and that the vehicle is not unevenly loaded.

Increased brake pedal travel

The brake circuit is out of order. Check if brake fluid is leaking.

The brake pedal springs and sinks

1. Air in the brake system. Remove air from the system.

2. Not enough fluid in the reservoir. Add new brake fluid, remove air from the system.

3. Formation of steam bubbles. Occurs mainly under heavy load on the brakes. Replace the brake fluid, bleed air from the system.

Reduced braking effect, pedal falls through

1. Leaky piping. Tighten piping connections or replace pipes.

2. Damage to the seals in the master or working brake cylinders. Replace the seal. In the master brake cylinder, replace the internal elements, if necessary, replace the master cylinder

3. The rubber gasket is damaged. Repair the caliper.

Poor braking despite high pedal force

1. The brake linings are oily. Replace the brake pads.

2. Incorrect or hardened brake pads installed. Replace the pads. Install genuine AUDI pads.

3. The brake booster is faulty. Check the brake booster.

4. The brake pads are worn out. Replace the brake pads.

When braking, the car pulls to the side

1. The tire pressure is not correct. Check and correct the tire pressure.

2. Uneven tire wear. Replace worn tires.

3. The brake pads are oily. Replace the pads.

4. Different brake pads are installed on one axle. Replace the pads. Install original AUDI pads.

5. Poor condition of brake pads. Replace the pads.

6. The caliper wells are dirty. Clean the guides and seating surfaces of the pads in the caliper.

7. Corrosion of brake caliper cylinders. Replace the caliper.

8. Uneven brake pad wear. Replace brake pads (on both wheels).

The brake tightens by itself

1. The compensation hole in the master brake cylinder is clogged. Clean the master cylinder and replace the internal components.

2. The clearance between the drive rod and the master cylinder piston is too small. Check the clearance.

Brakes get hot while driving

1. The compensation hole in the master cylinder is clogged. Clean the master cylinder and replace the internal components.

2. The clearance between the drive rod and the master cylinder piston is too small. Check the clearance.

3. The throttle hole in the special valve on the bottom is clogged. Clean the main brake cylinder, replace the internal elements and brake fluid.

The brakes are shaking

1. The brake pads are of the wrong type. Replace the pads, install genuine AUDI pads.

2. The brake disc is corroded in places. Carefully polish the brake disc.

3. The brake disc has lateral runout. Treat or replace the disc.

The brake pads do not move away from the brake disc, the wheel is difficult to turn by hand

Corrosion in brake caliper cylinders. Repair the caliper, possibly replace it.

Uneven wear of brake pads

1. The wrong type of brake pads are installed. Replace the pads, install original AUDI pads.

2. The caliper is dirty. Clean the caliper well.

3. Heavy piston stroke. Fix it.

4. The brake system is not sealed. Check the sealing of the brake system.

Wedge-shaped wear of brake pads

1. The brake disc does not rotate parallel to the caliper. Check the caliper mating surfaces.

2. Corrosion in the calipers. Remove contamination.

3. The piston is not working properly. Check the piston position.

Squeaking brakes

1. Often the reason is atmospheric influence (air humidity). If the creaking appears after a long period of standing in high humidity and then disappears, there is no need to do anything.

2. The wrong type of pads are installed. Replace the pads, install original AUDI A3 pads, cover the base plates with anti-squeak paste.

3. The brake disc does not rotate parallel to the caliper. Check the mating surfaces of the brake caliper.

4. The caliper shaft is dirty. Clean the caliper shaft

5. The brake shoe mounting springs are bent. Replace the mounting springs.

6. The pressure springs are stretched. Replace the pressure springs.

Brake pedal pulsation

1. ABS in action. Normal, no help needed.

2. Brake disc lateral runout or thickness tolerance too large. Check runout and thickness. Rework or replace disc.

3. The brake disc does not rotate parallel to the caliper. Check the caliper mating surface.

ABS warning light comes on while driving

1. The supply voltage is too low (below 10 V). Check the voltage. Check whether the generator indicator lamp goes out after the engine is started. If everything is OK, check the generator drive V-belt.

2. ABS damage. Check for reliable contact and corrosion of the ground connection at the return pump (in the hydraulic block).

Suspension and steering

The car pulls to one side when moving

1. The tires are unevenly inflated.

2. There is a defect in the tires.

3. Excessively worn suspension or steering components

4. It is necessary to adjust the front wheel alignment angles.

5. The front brakes are seized

There is jerking, twitching or vibration

1. Wheel balance is broken or rims are out of ovality. Have them balanced at a tire shop.

2. Wheel bearings are worn out, their tightening force is weakened or their adjustment is disturbed

3. Shock absorbers or other suspension components are worn or damaged

There is excessive rocking of the car or "digging" of the nose when turning or braking

1. The shock absorbers are faulty. Replace the entire set

2. Broken or weakened springs and/or other suspension components. Check the condition of the components

The steering wheel is too hard to turn

1. The fluid level in the power steering reservoir has dropped excessively

2. The tires are not inflated correctly.

3. The steering joints are not sufficiently lubricated

4. The front wheel alignment angles are out of adjustment.

5. The power steering does not develop the required power

There is excessive play in the steering

1. The tightening force of the front wheel bearings has weakened

2. Excessively worn suspension or steering components

The power steering system does not develop the required force

1. The power steering pump drive belt is worn or damaged, or its tension adjustment is incorrect

2. The hydraulic fluid level has dropped excessively

3. The hydraulic system hoses or lines are clogged. Check and replace if necessary.

4. There is air in the hydraulic system. Bleed the system

There is excessive wear on the treads (not in one particular area)

1. The tires are not inflated correctly.

2. Wheel balance is out of order. Contact a tire shop.

3. Wheel rims are damaged. Check and replace if necessary.

4. Suspension or steering components are excessively worn.

There is excessive wear on the outer edge of the treads

1. The tires are not inflated correctly.

2. The turns are too sharp. Reduce speed.

3. Front wheel alignment is out of adjustment (excessive convergence). Contact a workshop for professional adjustment.

4. The suspension arm is bent or twisted.

There is excessive wear on the inner edge of the treads

1. The tires are not inflated correctly.

2. Front wheel alignment is out of adjustment (divergence). Have the adjustment done at a car service workshop.

3. Steering components are damaged or loose.

There is localized wear of the tread

1. Wheel balance is disturbed.

2. The discs are damaged or bent. Check and replace if necessary.

3. There is a defect in the tires.

Windscreen wiper blade defects

Slippage

1. The rubber bands are dirty. Clean the rubber bands with a stiff nylon brush and a detergent solution or alcohol.

2. The edges of the brushes are frayed, the rubber bands are worn or torn. Replace the rubber bands.

3. Old rubber bands, cracked surfaces. Replace rubber bands.

In the cleaning field, the remaining water immediately collects into drops

The windshield is contaminated with varnish polish or oil. Clean the windshield with a clean cloth and remover of grease, oil, silicones.

The brush cleans one-sidedly - one way is good, the other is not

1. The rubber band is deformed to one side "does not tip over anymore". Install a new rubber band.

2. The wiper arm is twisted, the blade does not fit precisely on the glass. Carefully turn the arm until the vertical position is reached.

Uncleaned surfaces

1. The elastic has come loose from the frame. Carefully insert the elastic into the frame.

2. The wiper blade does not fit evenly to the glass because the spring bars or plates are bent. Replace the wiper blade. This fault primarily occurs when the replacement blade is installed carelessly.

3. The force of the lever is too low. Lightly lubricate the wiper arm pivots and springs or install a new arm.

Tyre defects

Severe tire wear on both sides of the working surface

Tire pressure too low.

Severe wear of the tire in the middle of the working surface, around the entire circumference

Tire pressure is too high.

Uneven tread wear

Static and dynamic imbalance of the wheel. Possibly too much lateral runout of the disc, too much play in the bearing joints.

Uneven wear in the middle of the tread

Static wheel imbalance. Possible consequence of strong vertical runout.

Severe wear in certain areas in the middle of the working surface

Traces of blocking under full braking.

Saw-tooth tread wear. Often with a tear in the fabric base that is not visible from the outside

Overloading the vehicle. Check the inside of the tire for base tears.

Rubber tongues on the side edges of the tread

Incorrect wheel alignment. Tire is worn. Also check the condition of the shock absorber on the rear wheels.

Formation of burrs on one side of the front wheel tread

Incorrect toe adjustment. Tire is worn. Frequent driving on wavy surfaces. Fast driving on turns.

Cord breaks. At first only visible from the inside

Driving over sharp rocks, tire impacts, etc. at high speed.

One-sided worn working surface

1. Check the camber adjustment.

2. ABS damage. Check the reliability of the connection to the housing at the return pump (in the hydraulic block).