Diagnostic Trouble Code (DTC) Information ECM-21AD

Condition 

The engine control module (ECM) receives information from the heated oxygen sensor (HO2S) about fuel / air mixture at both the upper and lower part-load range. If the fuel / air mixture deviates from λ=1, the short-term fuel trim will compensate for this by adjusting the injection time so that λ=1 is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. The diagnostic trouble code (DTC) will be stored when the long-term trim must be adjusted almost to maximum in the upper and lower part-load ranges.

The diagnostic trouble code (DTC) can be diagnosed when driving under specific driving conditions.

Substitute Value 

None.

Possible Source 

• Air leakage in the intake system
• High fuel pressure
• Leaking injectors
• Damaged mass air flow (MAF) sensor
• Contaminated engine oil
• Oil level too high
• Damaged heated oxygen sensor (HO2S).

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit.