VOLVO
ECM-0031 - Front heated oxygen sensor (HO2S), bank 1 heating. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
According to the engine control module, the voltage in the heater circuit of the front oxygen sensor is wrong, and that is why the code is set. The fault appears while driving, and the malfunction indicator lamp comes on while the code is active. The code does not affect drivability.
Possible causes
- The signal wire is shorted to supply voltage
- The signal wire is shorted to earth
- Damaged front oxygen sensor
What you can do
- 1Check the wires and connectors to the oxygen sensor. Look for play, contact resistance and oxidation
- 2Measure with a multimeter that the signal wire to the heater circuit has no break and is not shorted to earth
- 3Measure with a multimeter that the signal wire to the heater circuit is not shorted to supply voltage
- 4Clear the fault code and road test the car. If it returns after these checks, have a workshop replace the front oxygen sensor
- 5Put right any wires or connectors found to be faulty before the oxygen sensor is replaced
Symptoms you may notice1
- The malfunction indicator lamp is on
General guidance for car owners. Diagnosis on the car can point to a different cause.