On Board Diagnostic (OBD), characteristics

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

When malfunctions occur in monitored sensors or components, Diagnostic Trouble Codes (DTCs) are stored in DTC memory with a description of the malfunction type.

The Engine Control Module (ECM) selects from all possible Diagnostic Trouble Codes (DTCs) according to its evaluation of the malfunction information. Refer to DTC table. Refer to Diagnostic Trouble Code (DTC) table: SAE P0-Codes or refer to Diagnostic Trouble Code (DTC) table: SAE P1-Codes and stores this code until DTC memory contents are erased.

Malfunctions that occur only intermittently (sporadically) are printed out with the added text "sporadically occurring malfunction". These malfunctions are indicated on the display with the added text "/SP". Sporadic malfunctions are frequently caused by loose contacts or brief open circuits. A sporadic malfunction will be erased if it no longer occurs after 40 warm-up cycles (engine started with coolant temperature below 50 ° C - switched off above 72 ° C)

Stored DTCs can be identified using the VAG1551 or VAG1552 Scan Tools or the new VAS5051 tester. Refer to DTC memory of Engine Control Module (ECM), checking (scan tool function 02) and erasing (scan tool function 05) .

DTC memory must be erased after malfunctions are repaired. Refer to DTC memory of Engine Control Module (ECM), checking (scan tool function 02) and erasing (scan tool function 05) and the readiness code must be re-generated. Refer to Readiness code, generating .

When DTC memory is erased, the Engine Control Module (ECM) forgets all oxygen sensor and charge pressure adaptation values. Depending on vehicle's mileage, this can cause substantial problems with running characteristics.

If connectors are disconnected from the 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, engine must be allowed to run at idle for a few minutes or a longer road test must be performed until the adaptation procedure has been completed. Procedure to follow after open circuit in voltage supply. Refer to Procedure after voltage supply open circuit .

NOTE: General information regarding On Board Diagnostic (OBD) can be found in the operating instructions for the VAG1551, VAG 1552 or the new VAS5051 tester.