Diagnostic trouble code (DTC) information
WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Condition
The rear heated oxygen sensor (HO2S) signal is checked when the control module carries out a three-way catalytic converter (TWC) diagnostic. A diagnostic trouble code (DTC) is stored if the rear heated oxygen sensor (HO2S) signal is not within the range permissible for three-way catalytic converter (TWC) diagnostics. Diagnostic trouble code (DTC) ECM-1A is stored if the signal from the rear heated oxygen sensor (HO2S) is too high, too low or missing.
Substitute Value
- Fuel trim disabled
- Three-way catalytic converter (TWC) diagnostic disabled.
Possible Source
Signal too high:
- Contact resistance in the terminals
- Short-circuit to supply voltage in the signal cable
- Defective rear heated oxygen sensor (HO2S).
Signal too low:
- Contact resistance in the terminals
- Short-circuit to ground in signal cable
- Air leakage in the intake system
- Defective rear heated oxygen sensor (HO2S).
Signal missing:
- Contact resistance in the terminals
- Open-circuit in the signal cable
- Defective rear heated oxygen sensor (HO2S).
Fault symptom[s]
- Malfunction indicator lamp (MIL) lit.