VOLVO
ECM-1836 - Relay, engine coolant heater 2. Signal too low
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) has registered that the control signal to the relay for engine coolant heater 2 is too low. The relay switches the electric coolant heater in the cooling system. The code is most often caused by an open circuit or a short to ground in the wire, but a defective relay can also set it.
Possible causes
- Open circuit in the control wire to the relay for coolant heater 2
- Control wire short-circuited to ground
- Defective relay for engine coolant heater 2
What you can do
- 1Read and clear the fault code, then check whether it returns
- 2Check that the fuse for engine coolant heater 2 is intact
- 3Check that the relay sits firmly in the fuse and relay box in the engine compartment and that its contacts are not oxidised
- 4Use a multimeter to check that the wire to the relay has no open circuit and is not short-circuited to ground (body)
- 5If you have a diagnostic tool, activate engine coolant heater 2 and listen for the relay to click
Symptoms you may notice1
- No noticeable symptoms for the driver
What the fault can affect1
- The control module assumes a fixed value for the relay instead of the actual signal
General guidance for car owners. Diagnosis on the car can point to a different cause.