VOLVO
ECM-6630 - Glow plug. 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 found a fault in the signal from the glow plug relay, and the fault may also concern the glow plug circuit when it sits outside its normal signal range. If the wiring to the glow plugs touches supply voltage, or if a glow plug is shorted, the engine can become difficult to start.
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
- 1Use a multimeter to check that the wires from the relay to the glow plugs have no contact with supply voltage
- 2If you have a diagnostic tool, activate the glow plug relay and see whether battery voltage drops while the glow plugs receive current
- 3Have a workshop measure the glow plugs for short circuits
- 4Replace the glow plug relay if the wiring is sound but the fault remains
Symptoms you may notice1
- The engine is hard to start
General guidance for car owners. Diagnosis on the car can point to a different cause.