P0691

Fan 1 Control Circuit Low

Engine cooling Generic OBD-II High

What it means

P0691 means the control circuit for cooling fan 1 is reading low — typically shorted to ground — so the computer can't command the fan normally. The engine's cooling fans pull air through the radiator at low speed and idle, so this fault mainly risks overheating in slow traffic rather than affecting how the engine starts.

High

Can I keep driving? Watch the temperature gauge — a cooling-fan fault can let the engine overheat in traffic or at idle, so avoid stop-and-go driving until it's fixed.

Real-world scan data

Seen in

522

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0691 scans

P0693in 41.8% of scans

P1646in 17.8% of scans

P0645in 16.5% of scans

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 overheating in traffic, at idle, or at low speed
Cooling fan not running when it should (or running constantly)
Weak air-conditioning performance at idle

Common causes

Most likely first

Short to ground in the fan 1 control circuit wiringLikely
Failed cooling-fan relay or fan control moduleCommon
Faulty cooling-fan motorCommon
ECM/PCM driver faultLess often

How to diagnose & fix

Work through it in order

Scan and confirm the code, then watch whether the fan runs as the engine heats up.
Inspect the fan control wiring for a short to ground or chafing.
Test the fan relay/module and the fan motor directly.
Repair wiring or replace the relay/fan as needed; confirm the fan cycles, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0691?+

Only cautiously — highway driving may be fine because airflow cools the radiator, but idling or crawling in traffic can overheat the engine. Fix it soon to avoid heat damage.

Can I just clear P0691?+

It returns if the circuit fault remains, and clearing it does nothing for the overheating risk.

Read & clear P0691 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