Powertrain
generic / SAE
P0686
ECM/PCM Power Relay Control Circuit Open
The control circuit for the ECM main power relay is open. Without this relay, the controller cannot maintain its keep-alive supply.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number6 / 86
Possible causes
- Main relay defective high
- Relay control wire open medium
- Pin pushed back out of connector body low
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–400 €
- Estimated time: 0.3–2 h
- Component: ecm
- Component: main relay
- Component: relay wiring
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012