VOLVO
ECM-240D - Front heated oxygen sensor (HO2S), bank 1, heating. Signal too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS40 (2004–2013), V50 (2004–2013)
Show models by year and engine (2)
What does this fault code mean?
The engine control module (ECM) measures the resistance in the heater circuit of the front oxygen sensor on bank 1. The code is set when that resistance is too low. Connection problems or a damaged sensor may lie behind the fault.
Possible causes
- Contact resistance and oxidation in the connections
- Damaged front oxygen sensor
What you can do
- 1Read and clear the code, then road test to see whether it returns
- 2Check that the connector to the front oxygen sensor is secure and dry
- 3If possible, measure from the back of the connector so that it is not damaged
- 4Do not use rust solvent spray or grease in the sensor connector
- 5If the fault remains, have a workshop decide whether the front sensor needs replacing
Symptoms you may notice1
- Malfunction indicator lamp (MIL) lit
General guidance for car owners. Diagnosis on the car can point to a different cause.