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DTC code page

P0690: ECM/PCM Power Relay Sense Circuit High

Quick answer: The PCM saw the relay-output feedback stay higher than expected or electrically biased high.

Drivers also search this fault as PCM power relay sense high, ECM relay feedback high, PCM relay output high.

Severity: high Family: powertrain Related paths: 14
Meaning

What P0690 usually means

P0690 is the high-side feedback version of the PCM power-relay sense family. The module thinks the monitored relay output is higher than expected or present when it should not be. That can happen with a short to power, backfeed through another circuit, a stuck relay, or a sense wire that never drops to the expected state after key-off.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Ask whether the battery goes dead or the PCM seems to stay awake after shutdown.
  • Check whether relay output remains live with the key off.
  • Inspect for wiring repairs, accessories, or fuse-box damage that could create a backfeed path.
Driving risk

Can you keep driving?

P0690 can leave the vehicle with battery drain, intermittent starts, or unpredictable PCM behavior. Solve it before trusting the vehicle for normal daily use.

High urgency: If symptoms are active, reduce driving and diagnose quickly before secondary damage builds.
Likely causes

Common causes behind this code

  • Sense wire shorted to battery voltage
  • Relay output staying live because the relay is stuck or back-fed
  • Fuse-box cross-feed or wiring damage
  • Module or driver issue preventing normal shutdown logic
  • Aftermarket wiring modification feeding the PCM path incorrectly

Cause phrases often tied to this code: sense circuit high, short to power, backfeed, stuck relay, parasitic draw.

Diagnostic order

Suggested workflow

  1. Review freeze-frame and customer complaint timing around shutdown, restart, and overnight drain.
  2. Measure relay-output and sense-circuit voltage with key on and key off.
  3. Inspect for short-to-power, backfeed, or stuck-relay conditions.
  4. Verify that the PCM feed powers down normally after the repair.
  5. Retest for battery drain and repeat-code return over several key cycles.
Avoid guesswork

Common mistakes

  • Replacing the battery repeatedly while a stuck relay or backfeed keeps draining it.
  • Ignoring aftermarket add-ons that share power near the fuse box.
  • Confusing a sense-high code with simple overcharging.
Repair path

Practical fix guidance

  • Repair the high-feedback condition by fixing the short, backfeed, relay, or fuse-box problem proven by testing.
  • Then confirm normal shutdown current draw and PCM sleep behavior.
  • If other voltage-related codes remain, verify charging performance separately.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0690

Useful when the driver knows the wording but not the exact DTC yet.

  • PCM power relay sense high
  • ECM relay feedback high
  • PCM relay output high
Related search intent

Queries this page can answer naturally

  • P0690 code meaning
  • what does P0690 mean
  • PCM power relay sense circuit high
FAQ

Quick questions about P0690

Can P0690 cause an overnight dead battery?

Yes. If relay output or PCM feed stays active after shutdown, parasitic draw can kill the battery.

Is P0690 the same as a charging-system high-voltage code?

No. It is about the PCM power-relay sense path being biased high or staying powered, not simply alternator output being high.

What should I test first with P0690?

Test whether the relay output actually powers down after key-off. That quickly separates a real stuck-power condition from guesswork.