On Board Diagnostic Function

The Engine Control Module (ECM) for the Turbo-Diesel Direct Injection (TDI) system is equipped with a Diagnostic Trouble Code (DTC) memory.

If malfunctions occur in monitored sensors and components, they will be stored in the DTC memory together with an indication of the type of malfunction.

Malfunctions which only occur sporadically will also have the "sporadic malfunction" code "/SP" added to the print out. The cause of sporadic malfunctions can be e.g. a loose terminal or a brief open circuit. If a given sporadic malfunction does not occur again within 40 warm-up cycles, it will be erased from DTC memory.

A warm-up cycle is defined as each engine start where coolant temperature is below 49°C (120°F) and the engine is continuously run until a coolant temperature of 71°C (160°F) is reached.





NOTES:
- If malfunctions are recognized that could cause emission levels to exceed specifications, the Malfunction Indicator Lamp (MIL)
lights up
- If malfunctions that affect vehicle handling are recognized, the Glow plug indicator light flashes
- Stored malfunctions can be displayed via the VAG 1551 or 1552 Scan Tool. Reading Diagnostic Trouble Codes
- Print-outs are only possible with the VAG 1551 Scan Tool, the VAG 1552 does not have an on-board printer
- DTC memory must be erased once the malfunctions have been eliminated. Clearing Diagnostic Trouble Codes
- After erasing DTC memory the readiness code must be created.