Diagnostic Trouble Code (DTC) Information ECM-29

Diagnostic trouble code (DTC) information ECM-29

Condition
The engine control module (ECM) checks the change over time from rich to lean air-fuel mixture using the signal from the rear heated oxygen sensor (HO2S). During engine braking (fuel shut-off), the fuel-air mixture is leaner. This means that the signal from the rear heated oxygen sensor (HO2S) should fall to a certain level. Diagnostic trouble code (DTC) ECM-29 is stored if the signal from the rear heated oxygen sensor (HO2S) drops too slowly or does not fall at all during engine braking.

Substitute value
- Fuel trim disabled
- Three-way catalytic converter (TWC) diagnostic disabled.

Possible source
- Contact resistance in the terminals
- Leakage in the exhaust system
- Defective rear heated oxygen sensor (HO2S).

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