VOLVO
ECM-P256800 - Direct Ozone Reduction Catalyst Temperature Sensor Circuit Range/Performance. General Failure Information. No sub type information
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsS80 (2007–), V70 (2008–), XC60 (2009–), XC70 (2008–)
Show models by year and engine (7)
What does this fault code mean?
The engine control module (ECM) compares the radiator temperature sensor signal with the ambient and coolant temperatures at certain times. The code is set when the radiator changes temperature in a way that does not match the other temperatures. The fault may lie in the sensor, the radiator, the electric cooling fan or another temperature-related fault. Even though the code is named after a catalyst temperature sensor, it concerns the radiator temperature sensor.
Possible causes
- Another temperature-related fault in the control module, which should be traced first
- Electric cooling fan performance too low
- Contact resistance and oxidation in the connections
- Damaged radiator
What you can do
- 1Read the codes for other temperature sensors and fix those first, since this code can be caused by one of them
- 2Check that the electric cooling fan starts and runs, because this code can appear when it does not work
- 3If you have a diagnostic tool: activate the electric cooling fan and listen for it to start
- 4Check that the connector to the radiator temperature sensor is firmly seated and free from oxidation
- 5Look over the radiator for external damage
- 6If none of this finds anything, have a workshop decide whether the radiator or the sensor needs replacing
Symptoms you may notice1
- Emissions warning light comes on
General guidance for car owners. Diagnosis on the car can point to a different cause.