P0690 ECM/PCM Power Relay Sense Circuit High

P0690 indicates a high condition in the ECM or PCM power relay sense circuit. The module sees relay output or sense voltage above the expected range.

Code details

Generic OBD-II · P0

System: Computer
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not leave a backfed PCM power circuit unresolved because it can cause battery drain and unpredictable module behavior.

Symptoms of P0690

Check-engine light, sometimes with several unrelated codes at once.
Warning lights, a no-start, or intermittent electrical faults.
Communication or module-reset problems on a scan tool.

Common causes of P0690

Low battery voltage, poor grounds, corroded connectors, or blown fuses.
Wiring or network (CAN bus) faults between modules.
A module software/programming issue, or rarely a failed controller.

Useful checks before replacing parts

Check relay sense voltage, relay command, ignition state, charging voltage, PCM power feeds, freeze-frame data, and symptoms of modules staying powered.
Inspect for short-to-voltage faults, stuck relay contacts, backfeed through aftermarket equipment, open grounds, crossed wiring, and fuse block corrosion.
Confirm whether the sense circuit remains high with the relay removed or ignition off to separate relay and harness faults.

Related OBD-II codes

These nearby computer entries can help compare wording and pin down the fault area.