Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information

Condition




The control module continuously checks three-way catalytic converter (TWC) effectiveness by comparing signals from the rear heated oxygen sensor (HO2S) with the front heated oxygen sensor (HO2S). Diagnostic trouble code (DTC) ECM-4901 is stored if three-way catalytic converter (TWC) efficiency deviates too much.

Substitute value
Rear heated oxygen sensor (HO2S) is disabled.

Possible source
- misfiring
- air leakage in the intake system
- air leakage in the exhaust system
- faulty fuel pressure?
- uneven compression?
- defective three-way catalytic converter (TWC)

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