VOLVO
ECM-P256702 - Direct Ozone Reduction Catalyst Temperature Sensor Circuit. General Failure Information. General signal failure
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) communicates all the time with the radiator temperature sensor on the radiator over the LIN network. Even though the code is named after a catalyst temperature sensor circuit, it concerns the radiator temperature sensor. The code is set when the module finds that the signal from that sensor is wrong.
Possible causes
- Low coolant level
- Contact resistance and oxidation in the connections
- Damaged radiator
What you can do
- 1Check the coolant level, since a low level can trigger this code
- 2Check that the connector on the radiator temperature sensor is firmly seated and free from oxidation
- 3Look over the radiator for external damage and wear
- 4The sensor is fixed to the radiator at the factory; check that it has not come loose or been knocked
- 5If none of this helps, have a workshop decide whether the radiator needs replacing, as the sensor is built into it
Symptoms you may notice1
- Emissions warning light comes on
General guidance for car owners. Diagnosis on the car can point to a different cause.