VOLVO
ECM-250C - Front heated oxygen sensor (HO2S), bank 2, heating. 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 engine control module (ECM) checks the resistance in the preheating circuit of the front oxygen sensor on bank 2. If the resistance is too high, the code is stored. The cause can be poor contact at the connections or a damaged sensor.
Possible causes
- Contact resistance and oxidation at the connections
- Damaged front heated oxygen sensor
What you can do
- 1Read the code, clear it and road test to see whether it comes back
- 2Look at the oxygen sensor connector on bank 2 for oxidation and loose connections. Rust solvent spray and grease must not be used on it
- 3If possible, measure from the cable side of the connector so it is not damaged
- 4If the connector is clean but the fault remains, have a workshop try a new front oxygen sensor
Symptoms you may notice1
- The malfunction indicator lamp (MIL) is lit
General guidance for car owners. Diagnosis on the car can point to a different cause.