VOLVO
ECM-0425 - Catalytic converter temperature sensor. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS40 (1996–2004), V40 (1996–2004)
Show models by year and engine (2)
What does this fault code mean?
The engine control module (ECM) monitors the temperature sensor in the catalytic converter and sets the fault when the signal stays outside its normal range for a period of time. This happens after engine braking, when the engine is warm and the engine speed is high. The cause may be contact resistance, an open or shorted signal or ground wire, or a defective temperature sensor.
Possible causes
- Contact resistance in the connections
- Open circuit or short to ground or voltage in the signal wire
- Open circuit in the ground wire, or ground wire shorted to voltage
- Defective catalytic converter temperature sensor
What you can do
- 1Read out the fault code, erase it and road-test to see whether it returns
- 2Switch off the ignition and check the connections to the control module and the converter temperature sensor for contact resistance and oxidation
- 3Use a multimeter to check that the wires to the temperature sensor have no open circuit and no short to ground or voltage
- 4If you have a diagnostic tool, read the catalytic converter temperature in live data during a road test and see whether the value rises as the engine warms up
- 5If the fault remains, have a workshop with diagnostic equipment check the catalytic converter temperature sensor and replace it if needed
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.