Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information ECM-221C

Condition




The engine control module (ECM) monitors the operation of the rear heated oxygen sensor (HO2S) by checking its signal. The engine control module (ECM) checks that the probe has registered a rich fuel/air mixture. If this is not the case, the engine control module (ECM) changes the fuel/air mixture. The diagnostic trouble code (DTC) is stored if the rear probe has still not registered a rich fuel / air mixture.

Note! At fuel shut-off, the probe must show a lean fuel/air mixture. The diagnostic trouble code (DTC) is stored if the switch-over time to a lean fuel/air mixture is too long.

Substitute value
None.

Possible source
- Leakage in the exhaust system
- Damaged rear heated oxygen sensor (HO2S).

Fault symptom[s]
- Malfunction indicator lamp (MIL) lit.