Diagnostic trouble code (DTC) information

Condition 

The control module receives information from the heated oxygen sensor (HO2S) about the fuel / air mixture. 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. Diagnostic trouble code (DTC) ECM-278A will be stored if the short-term fuel trim deviates (when long-term fuel trim diagnostics are activated) too much from the center position (value) for bank 2 (cylinders 4, 5 and 6).

Diagnostic trouble code (DTC) ECM-268A is stored for bank 1 (cylinders 1, 2 and 3).

Substitute Value 

none

Possible Source 

Upper limit 

• intake air leakage
• exhaust system air leakage
• low fuel pressure
• defective heated oxygen sensor (HO2S).

Lower limit 

• intake air leakage
• high fuel pressure
• leaking injectors
• defective mass air flow (MAF) sensor
• contaminated engine oil
• oil level too high
• defective heated oxygen sensor (HO2S).

Fault symptom[s] 

• none.