VOLVO
ECM-232C - Rear heated oxygen sensor (HO2S), bank 2. Signal too high
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 above its permitted range. The fault can come from the signal or ground wire touching a supply voltage, or from a damaged sensor. Oxygen sensor control is switched off while the fault is present.
Possible causes
- Short-circuit to supply voltage in the signal wire
- Short-circuit to supply voltage in the ground wire
- Damaged rear oxygen sensor
What you can do
- 1Read and clear the code, then road test to see whether it comes back
- 2Look for chafed wiring near the sensor where the signal or ground wire may have touched a live part
- 3With the sensor connector unplugged, use a multimeter to check whether the ground wire has voltage to the body when the ignition is on
- 4If you have a diagnostic tool: see whether the bank 2 sensor signal stays constantly high and does not move while the engine runs
- 5If the fault remains after these checks, have a workshop decide whether the sensor should be replaced
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lit
What the fault can affect2
- Rear oxygen sensor control after the catalytic converter is switched off
- Catalytic converter diagnostics are switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.