TorqueMech OBD Code Guide
P0688 - ECM/PCM Power Relay Sense Circuit/Open
The ECM detected an open or fault in the ECM/PCM power relay sense circuit.
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Check likely system
Estimate after confirmation
Code Overview
The ECM detected an open or fault in the ECM/PCM power relay sense circuit.
Common Causes
- Relay, module, sensor, or control-circuit fault
- Damaged wiring or connector
- Power-supply or ground issue
Diagnostic Steps
- Inspect related relay, connector, and harness condition
- Check power, ground, and control signal where applicable
- Review companion codes before replacing parts
Related OBD Codes
Browse nearby codes when systems overlap.
Next Steps
Move from code to checks, then estimate.