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.
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.
Related codes
Often seen with P0691
Read & clear P0691 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX