Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information

Condition




Diagnostic trouble code (DTC) ECM-990A is stored if the engine control module (ECM) registers that the nominal idle speed (engine coolant temperature (ECT) above 60°C) deviates, either in being 200 rpm over or 100 rpm below the nominal idle speed.

Substitute value
None.

Possible source

Faulty signal:
- Search the air and fuel supplies in the fuel system for the fault cause (air leakage, blockages etc).
- Incorrectly adapted electronic throttle unit.

Fault symptom[s]
- Malfunction indicator lamp (MIL) lit
- High idling speed
- Low idling speed