P0689

ECM/PCM Power Relay Sense Circuit Low

Q: Is it safe to drive with P0689?

Not really — this circuit confirms power to the engine computer, so a fault can cause stalling or a no-start at any time. Have it diagnosed promptly.

Q: Can I just clear P0689?

You can, but if the relay or wiring is faulty the code returns and the car may stall; fix the circuit rather than clearing it.

ECM power supply Generic OBD-II High

What it means

P0689 means the engine computer sees a low voltage on the sense wire it uses to confirm its main power relay is delivering power. Because this relay feeds the ECM itself, a real fault here can cause stalling, hard starting, or a no-start, so it should be diagnosed rather than ignored.

High

Can I keep driving? Risky — this circuit powers the engine computer, so it can cause stalling or a no-start; get it diagnosed before relying on the vehicle.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Engine stalls or is hard to start / no-start
Intermittent power loss or erratic engine behavior
Other electrical or sensor codes appearing at the same time

Common causes

Most likely first

Faulty ECM/PCM main power relayLikely
Short to ground or low-voltage fault in the sense-circuit wiringCommon
Corroded or loose connector at the relay or ECMCommon
Poor battery or ground connection feeding the relayLess often
Faulty ECM/PCM (least likely)Less often

How to diagnose & fix

Work through it in order

Read all stored codes and note any companion power, charging, or communication codes.
Test the ECM power relay and, if possible, swap in an identical known-good relay.
Check the sense-circuit wiring and connectors for shorts to ground and corrosion.
Verify battery voltage and the engine/ECM ground connections.
If the relay and wiring test good, evaluate the ECM/PCM.

FAQ

Quick answers

Is it safe to drive with P0689?+

Not really — this circuit confirms power to the engine computer, so a fault can cause stalling or a no-start at any time. Have it diagnosed promptly.

Can I just clear P0689?+

You can, but if the relay or wiring is faulty the code returns and the car may stall; fix the circuit rather than clearing it.

Read & clear P0689 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX