VOLVO
ECM-255C - Front 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 ECM has found an internal fault in its control of the oxygen sensor on bank 2. Although the code concerns a signal that is too high, the fault lies in the control module. If the fault remains after checks, the engine control module is replaced.
Possible causes
- Damaged engine control module (ECM)
What you can do
- 1Read the code, clear it and road test the car to see whether it returns
- 2Check the condition of the battery and that its terminals are tight
- 3Check the earth points and the connectors to the engine control module for loose contact, oxidation and damage
- 4Have a workshop replace the engine control module if the fault remains after these checks
Symptoms you may notice1
- Malfunction indicator lamp (MIL) on
General guidance for car owners. Diagnosis on the car can point to a different cause.