Note: Please also refer to Section "Troubleshooting".
1. The ignition and fuel systems are interconnected components of the engine management system, so some of its components can also perform functions related to the fuel system.
2. The ignition and power supply systems have a common diagnostic system designed to store fault codes (DTC) and perform diagnostics. When a failure is detected, the control unit records the corresponding DTC code in memory, which can be read using a special scanner.
Note: Do not forget to clear the control unit memory after reading the fault codes and making the appropriate corrections.
3. Reading the information stored in the ECM memory in most cases allows you to determine the causes of engine failures. Analysis of the read information using the code list (see Specifications) allows you to localize the source of failure at the level of a specific element or its electrical wiring circuit.
Attention: Visual inspection of the wiring and connectors is not enough - be sure to read the information stored in the control unit memory!
4. OBD II DTCs are five-digit codes and can be identified by their alphanumeric structure. The code structure is described below using P0401 as an example (eGR adjustment, too much air mass):
1st sign:
- R - engine and transmission (Powertrain)
- B - Body
- C - Chassis
- U - data transmission systems
2nd sign:
- 0 - SAE/ISO standardized code
- 1 - code assigned by the manufacturer
- 2 - SAE/ISO standardized code (for P-codes only) or a code assigned by the manufacturer (for codes B, C and U)
- 3 - for P-codes: allocated area for standardized SAE/ISO codes (from R3000 to R3399) and for codes assigned by the manufacturer (from P3400 to P3999); for other codes - reserve area
3rd character for codes P0 and P1:
- 0 - fuel and air supply metering, additional equipment that reduces exhaust toxicity
- 1,2 - dosing of fuel and air supply
- 3 - ignition system
- 4 - additional equipment that reduces exhaust toxicity
- 5 - driving speed, idle parameters and other input data
- 6 - on-board computer and other output data
- 7-9 - transmission
- A - combined drive
- BF - reserve area
3rd character for P2 codes:
- A, 0-2 - fuel and air supply metering, additional equipment that reduces exhaust gas toxicity
- 3 - ignition system
- 4 - additional equipment that reduces exhaust toxicity
- 5 - additional input data
- 6 - on-board computer and other output data
- 7 - transmission
- 8 - reserve area
3rd character for RZ codes:
- 0-2 - fuel and air supply metering, additional equipment that reduces exhaust gas toxicity
- 3 - ignition system
- 4 - cylinder shutdown
- 5-9 - reserve area
- 3rd character for U-codes
- 0 - network power supply
- 1,2- network communication
- 3 - network software
- 4 - network data
The 4th and 5th characters are the ordinal numbering of individual units or systems.
The article is a reprint of material from audimanual