VOLVO
ECM-1121 - Engine temperature sensor. Signal faulty. Intermittent fault
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 has intermittently found a fault on the cable running from the engine temperature sensor, or that the sensor value has not changed after start-up. Engine management then uses a fixed value instead of the actual engine temperature. The fault is intermittent, so it may have cleared by the time the car reaches a workshop.
Possible causes
- Signal wire short-circuited to supply voltage
- Open circuit in the signal wire
- Defective engine temperature sensor
- Signal wire short-circuited to ground
What you can do
- 1Read and note the code, clear it and road test to see whether it returns
- 2Check the engine temperature sensor connector for play, contact resistance and oxidation
- 3Use a multimeter to check that the signal wire is not broken and has no contact with ground or voltage
- 4With your own diagnostic tool, check that the engine temperature rises as the engine warms up
- 5If the fault remains, have a workshop with diagnostic equipment check the sensor and the wiring
Symptoms you may notice1
- The malfunction indicator lamp comes on
What the fault can affect1
- The engine control module uses a fixed value for the engine temperature
General guidance for car owners. Diagnosis on the car can point to a different cause.