VOLVO
ECM-6620 - Glow plug control. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module has registered a faulty signal from the glow plug relay. It can also be set when the glow plug circuit misbehaves or sits outside its normal signal range.
Possible causes
- Short to supply voltage in the glow plug wires
- Short circuit in a glow plug
- Damaged glow plug relay
What you can do
- 1Check that the connectors at the glow plug relay and the glow plugs are secure and clean
- 2Use a multimeter to check that the wires between the relay and the glow plugs are not shorted to supply voltage
- 3Have a workshop activate the glow plug relay and check that battery voltage drops when it does
- 4Replace the glow plug relay if the wiring is sound but the fault remains
Symptoms you may notice5
- Poor performance and lack of power, especially when pulling away from a standstill
- The engine hesitates, surges or runs unevenly during acceleration
- The engine hesitates or runs unevenly at a steady speed
- The engine is hard to start and cranks slowly when cold
- The engine does not start and only turns over
General guidance for car owners. Diagnosis on the car can point to a different cause.