VOLVO
ECM-232D - Rear heated oxygen sensor (HO2S), bank 2. Signal too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS80 (1999–2006), XC90 (2003–)
Show models by year and engine (2)
What does this fault code mean?
The signal from the rear oxygen sensor on bank 2 is too low. The fault can come from the signal or ground wire being shorted to ground, but a damaged sensor can also set the code. Oxygen sensor control is switched off while the fault is present.
Possible causes
- Signal wire short-circuited to ground
- Ground wire short-circuited to ground
- Damaged rear oxygen sensor
What you can do
- 1Clear the code after reading it and road test to see whether it returns
- 2Inspect the signal wire for chafing or places where it may have touched the body
- 3With the sensor connector unplugged, use a multimeter to confirm that the signal and ground wires have no contact with the body
- 4If you have a diagnostic tool: read the sensor signal in live data and see whether it sits at a low value without moving
- 5If the fault remains, have a workshop try a new sensor
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lit
What the fault can affect2
- Rear oxygen sensor control is switched off
- Catalytic converter diagnostics are switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.