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P0691: Fan 1 control: circuit low

The ECU sees too low a voltage on the radiator fan control circuit; the fan may not run at all or may keep running all the time.

Code P0691 at a glance
CodeP0691
SystemEngine and transmission
GroupP06xx, Control unit and auxiliary outputs
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0691 means

The engine ECU runs the radiator fan, either directly, through a relay or through a small control module, to cool the engine when needed and whenever the air conditioning is on. This code means there is less voltage than expected on the fan 1 control circuit. Depending on how each manufacturer has designed it, that can leave the fan stopped or running non-stop.

Most common causes

  • Faulty fan fuse or relay
  • Loose or corroded fan or relay connector
  • Chafed control wire touching earth
  • Fan motor shorted or seized
  • Faulty fan control module
  • ECU fault (uncommon)

Symptoms

  • Fan not coming on, or running all the time
  • Temperature rising in traffic or at idle
  • Air conditioning cooling poorly when stationary
  • Engine warning light on

Can you drive with P0691?

With care You can drive, but keep an eye on the temperature gauge: if the fan is not working the engine can overheat in traffic. If it climbs above normal, stop and let it cool.

How to check it

With the engine warm at idle, or with the air conditioning switched on, the fan should start. Some scanners can switch it on in an actuator test to see if it responds.

How to read and clear P0691 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0691 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0691 is a generic code, so it means the same on any make, for example on Alfa Romeo, Cupra, Dacia, Jeep, Nissan, Škoda. See what Final OBD does on your car in makes and models.

What does code P0691 mean?

The engine ECU runs the radiator fan, either directly, through a relay or through a small control module, to cool the engine when needed and whenever the air conditioning is on. This code means there is less voltage than expected on the fan 1 control circuit. Depending on how each manufacturer has designed it, that can leave the fan stopped or running non-stop.

Can you drive with P0691?

You can drive, but keep an eye on the temperature gauge: if the fan is not working the engine can overheat in traffic. If it climbs above normal, stop and let it cool.

How do you clear P0691?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0691 comes back.