OBD-II code · Powertrain (generic)
P0689 ECM or PCM Power Relay Sense Circuit Low
The voltage sense line that confirms the main ECU power relay has actually closed reads low - either the relay is not closing or the sense line is shorted to ground.
Is it safe to drive with P0689?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyRelay does not close
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–1.8 h
- Emissions test
- Usually unaffected
- Parts involved
- Ecm Power Relay
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.