P0685 HONDA - Engine Control Module Power Relay Control Circuit Open
- Faulty Engine Control Module (ECM) power relay
- ECM power relay harness is open or shorted
- ECM power relay circuit poor electrical connection
- Blown ECM fuse
- Faulty ECM
Check all the Engine Control Module (ECM) fuses, if the fuses are OK, then replacing the ECM relay should take care of the problem.
- Engine Light ON (or Service Engine Soon Warning Light)