VOLVO
ECM-290A - Front heated oxygen sensor (HO2S), bank 2. Signal too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
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 fault concerns the front oxygen sensor on bank 2, which gives too high a signal. The control module compares the adaptation values of the front and rear sensors, and when they differ by more than the permitted amount the fault may lie in the front or rear sensor circuit.
Possible causes
- Air leakage in the exhaust system
- Signal cable or pump current wire touching supply voltage or ground
- Defective oxygen sensor
What you can do
- 1Check the exhaust system for air leaks, for example at joints and around the oxygen sensors
- 2Check the sensor wiring for chafing and pinching, and look for places where it could touch supply voltage or ground
- 3Do not use rust solvent or grease on the sensor connector
- 4If the wiring is in order and no fault is found, have a workshop replace both front oxygen sensors
- 5If the fault remains, it may be in the circuit of the rear sensor, so have that checked too
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.