Troubleshooting — Brake System (Audi A4 B7)

Note: 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 required pressure, that the front wheel alignment is correct, and that the vehicle is not unevenly loaded.

81. Brake pedal travel increased

1. The working circuit of the brake tract is damaged - check the system for leaks.

82. The brake pedal springs and sinks

1. Air has entered the brake system - bleed the system.

2. The fluid level in the master cylinder reservoir has dropped - make the appropriate adjustments, bleed the system.

3. Brake fluid boils in the hydraulic circuit. This occurs mainly when the brakes are heavily loaded. Replace the brake fluid, remove air from the system. Before driving, do not forget to release the parking brake.

83. Reduced braking efficiency, pedal sinks

1. The hydraulic circuit is not sealed.

2. The seals in the main or working brake cylinders are damaged.

84. The required braking efficiency is not achieved despite significant pedal force

1. The friction linings of the brake shoes are oily.



2. Incorrect or hardened brake pads are installed.

3. The brake booster is faulty.

4. The brake pads are worn out.

85. When braking, directional stability is impaired (the car pulls to the side)

1. The air pressure in the tires does not correspond to the required one.

2. The treads are unevenly worn.

3. Brake linings are oily.

4. Different brake pads/tires are installed on the same axle.

5. Brake pads are excessively or unevenly worn.

6. Wheel cylinders/caliper shafts are dirty.

7. The calipers are damaged by corrosion.

86. Unintentional braking occurs/brake mechanisms overheat

1. The compensation hole in the master brake cylinder is clogged.

2. The clearance between the drive rod and the master cylinder piston is insufficient.

87. Vibrations occur when braking (brake shudder)

1. The wrong type of brake pads are installed.

2. The brake disc is damaged in places by corrosion.

3. The runout value of the brake disc exceeds the maximum permissible value.

88. The brake pads do not move away from the brake disc, the wheel is difficult to turn manually

1. The caliper cylinders are damaged by corrosion.

89. There is uneven wear of the pads

1. The wrong type of brake pads are installed.

2. The calipers are damaged by corrosion.

3. The piston movement is difficult.

4. The hydraulic circuit of the brake system is not sealed.

90. There is wedge-shaped wear of the brake pads

1. The parallelism of the caliper relative to the brake disc is broken.

2. The calipers are damaged by corrosion.

3. The piston is not functioning properly.

91. There is a squeak when braking

1. Increased humidity of the atmospheric air. If the creaking occurs after a long period of parking in high humidity and then disappears, there is no need to worry.

2. The wrong type of brake pads are installed.

3. The parallelism of the caliper seat relative to the brake disc is broken.

4. The caliper shaft is dirty.

5. The brake shoe mounting springs are bent.

6. The pressure springs are stretched.

92. When braking, there is a distinct pulsation in the brake pedal

1. Sign of normal ABS operation (informative pedal).

2. The runout value of the brake disc exceeds the maximum permissible value.

3. The parallelism of the caliper seat relative to the brake disc is broken.

93. ABS warning light comes on while driving

1. Insufficient on-board supply voltage (below 10 V). Check whether the generator K/L goes out after the engine is started. If everything is OK, check the condition and tension of the generator drive belt.

2. There is a fault with the ABS - check the condition and reliability of the clamp connection of the ground of the return pump (in the hydromodulator).

The article was copied from the website: AUDImanual