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CoolingSeverity Medium: diagnose soon

P0691Fan 1 Control Circuit Low

What it means

The ECU sees an electrical fault in the circuit that switches cooling fan 1 (relay, module or the fan itself). If the fan doesn't run, the engine can overheat in traffic.

Symptoms

  • Temperature rises in slow traffic
  • Fan runs all the time or never
  • Air conditioning works poorly at standstill

Common causes

  • Faulty fan relay or fan control module
  • Seized or worn fan motor
  • Wiring or connector fault
  • Blown fan fuse

What to check first

  1. Command the fan with the scan tool
  2. Check fuse, relay and the fan supply under load
  3. Measure fan current and check the motor for tight spots
Can I drive with P0691? Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P0691: questions and answers

What does P0691 mean?

P0691: Fan 1 Control Circuit Low. The ECU sees an electrical fault in the circuit that switches cooling fan 1 (relay, module or the fan itself). If the fan doesn't run, the engine can overheat in traffic.

What are the symptoms of P0691?

Temperature rises in slow traffic. Fan runs all the time or never. Air conditioning works poorly at standstill.

What causes P0691?

Faulty fan relay or fan control module. Seized or worn fan motor. Wiring or connector fault. Blown fan fuse.

How do you diagnose P0691?

1. Command the fan with the scan tool 2. Check fuse, relay and the fan supply under load 3. Measure fan current and check the motor for tight spots

Can I drive with P0691?

Usually yes for a short distance, but performance or economy may suffer and the fault can get worse. Diagnose it soon.