VOLVO
ECM-0620 - Generator. Signal too low
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 ECM keeps an eye on the generator through a signal wire and sets the code when it registers a fault in how the generator is controlled. The causes given relate mainly to the signal wire to the generator, so the wiring is the first place to look.
Possible causes
- Open circuit in the signal wire to the generator
- Signal wire short-circuited to battery voltage or reference voltage
- Signal wire short-circuited to earth
What you can do
- 1With the ignition off, unplug the generator connector and check that its terminals are tight and free from oxidation
- 2Check the signal wire to the generator for breaks and chafing
- 3Use a multimeter to check that the signal wire has no contact with earth (the body) or with battery voltage
- 4If the wiring is intact and the fault remains, have a workshop assess whether the generator or its control needs replacing
Symptoms you may notice1
- No noticeable symptoms for the driver
General guidance for car owners. Diagnosis on the car can point to a different cause.