Diagnostic trouble code (DTC) information
Condition
The control module checks the rear heated oxygen sensor (HO2S) dynamics. The control module checks that the probe has registered both lean and rich fuel mixtures. If this is not the case, the control module alters the fuel mixture. Diagnostic trouble code (DTC) ECM-2A1A (bank 1) or 2B1A (bank 2) is stored if the rear probe is still not registering lean (signal too low) or rich (signal too high) fuel mixture. At fuel shut-off, the probe must show lean fuel mixture. Diagnostic trouble code (DTC) ECM-2A1A (bank 1) or ECM-2B1A (bank 2), signal missing, is stored if the switch-over time to lean fuel mixture is too long.
Substitute Value
- None.
Possible Source
- Leakage in the exhaust system
- Defective heated oxygen sensor (HO2S).
Fault symptom[s]
- The malfunction indicator lamp (MIL) lights.