P0691 code meaning
Fan 1 Control Circuit Low
Powertrain system Generic code P06xx codes Check engine light
What P0691 means
The engine module switches the radiator fan relays (or the input of a PWM fan module) through output drivers and checks each control circuit electrically. GM sets a short to ground or voltage at 0.5 Ω or less after 50 of 63 samples, with the lamp after two trips; GM Europe's 2011 Saab 9-5 covers P0691–P0696 with relay assignments, the Saab 9-4X's PWM fan module reacts within 1 s. P0691 means the fan 1 control circuit is shorted to ground. GM fixed a related problem with bulletin 16-NA-123, Ford with SSM 47999 for the 6.7 L diesel. The former title 'Cooling Fan 1' was shortened to the J2012 wording, as for P0480.
P0691 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0691
- Check engine light (GM after two trips)
- Fan runs constantly or not at all, depending on circuit design
- Rising coolant temperature in traffic or with A/C on
- A/C may be switched off to protect the engine
Common causes of P0691
- Most likelyControl wire to fan relay or module shorted to ground (chafing)
- Most likelyWater or corrosion in fan or relay connector
- PossibleFan relay faulty (coil shorted or low-resistance)
- Less likelyEngine module driver faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cooling fan relayFan control circuitEngine control module
What each part of P0691 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| 91 | The exact fault in that area. |
What to do next
- Note P0691 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0691
What does P0691 mean?
P0691 means "Fan 1 Control Circuit Low". The engine module switches the radiator fan relays (or the input of a PWM fan module) through output drivers and checks each control circuit electrically. It is a generic code, so it means the same on every make.
Is it safe to drive with P0691?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0691 fail an emissions test?
Yes, it can. P0691 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0691 to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0691 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.