Characteristics of On Board Diagnostic (OBD)

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The Engine Control Module (Motronic Engine Control Module -J220-) is equipped with DTC memory.

If malfunctions occur at the emissions relevant systems or components, they are stored in DTC memory with a description of the malfunction type.

The Engine Control Module (ECM) differentiates between different DTCs after evaluating the information, see DIAGNOSTIC TROUBLE CODE (DTC) TABLES: . The stored malfunctions can be checked with a standard diagnostic tester, see DIAGNOSTIC MODE 3: CHECK DTC MEMORY .

When harness connectors are disconnected from the Engine Control Module (ECM) or the battery is disconnected, all adaptation values in the control module are erased. DTC memory content will remain intact however. If the engine is started after this, a rough, uneven idle can result. In this case, the readiness code must be generated again, see READINESS CODE, GENERATING .

The following work steps must be performed in the described sequence after the malfunction(s) have been repaired:

-Check DTC memory, see DIAGNOSTIC MODE 3: CHECK DTC MEMORY .
-Erase DTC memory, see DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA .
-For completion, generate readiness code, see READINESS CODE, GENERATING .