VOLVO
ECM-253B - Front heated oxygen sensor (HO2S), bank 2. Signal missing
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?
Although the code is titled signal missing, it applies when the voltage used to heat the oxygen sensor on bank 2 disturbs the sensor's signal. The engine control module (ECM) stores the code when this happens.
Possible causes
- One of the heater cables is short-circuited to the sensor's other signal cables
- Damaged front heated oxygen sensor
What you can do
- 1Read and note the code, clear it and road test to see whether it returns
- 2Check the bank 2 oxygen sensor connector for a firm fit and cleanliness. Rust solvent spray and grease must not be used
- 3Follow the cables from the sensor and look for chafing, damaged insulation and places where two cables may have touched
- 4Use a multimeter to check that the heater cables are not short-circuited to the sensor's signal cables
- 5If the cables are intact, have a workshop decide whether the oxygen sensor needs replacing
Symptoms you may notice1
- The malfunction indicator lamp (MIL) is lit
What the fault can affect2
- 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.