VOLVO
EFI-0011 - Heated oxygen sensor (HO2S). Faulty signal
System
Electronic Fuel Injection (EFI)
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 modelsS40 (1996–2004), V40 (1996–2004)
Show models by year and engine (2)
What does this fault code mean?
The control module receives a faulty signal from the lambda probe. The fault may be in the probe itself, or in the connector or signal wire, where an open or short circuit can cause it.
Possible causes
- Defective lambda sensor
- Incorrectly connected connector, or an open or short circuit in the signal wire
What you can do
- 1Check that the connectors to the control module and the lambda sensor are secure and free from oxidation and contact resistance.
- 2Check the wires from the lambda sensor for breaks. With a multimeter you can check that the signal wire is not open or shorted to ground or voltage.
- 3If you have a diagnostic tool, read the lambda value in live data. See whether it swings between rich and lean once the engine is warm.
- 4If no fault is found in the connectors or wiring, the lambda sensor needs replacing. Have a workshop do this.
Symptoms you may notice2
- The malfunction indicator lamp lights up
- Poor performance
What the fault can affect2
- The engine runs only on a rich mixture of fuel and air
- Idle control has no damping
General guidance for car owners. Diagnosis on the car can point to a different cause.