Error code
OBD2 P0691
OBD2P0691
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
Fan 1 Control Circuit Low.
Severity
moderateCan be driven, but may experience overheating issues.
Summary
P0691 indicates that there is a low voltage issue with Fan 1 control circuit in the engine coolant blower motor.
Symptoms
- Poor air conditioning performance
- Engine overheating, especially at low speeds and stop-and-go traffic
Common Causes
- Wiring short to earth on the cooling fan motor
- Faulty relay or poor connections in the circuit
- Blown fuse
Diagnosis
- Check battery voltage with a multimeter (12.6V DC off, 13.8-14.5V DC on)
- Inspect fuses for continuity using an ohmmeter
- Test relays for proper operation and resistance
- Measure fan motor voltage with the air conditioning set to high
Fixes
- Replace faulty relay or fuse
- Repair wiring harness or replace cooling fan motor if necessary
FAQ
What should I do first when diagnosing P0691?
Start by checking the battery voltage and fuses to rule out simple issues.
How can I test the cooling fan motor?
Use a multimeter to measure voltage at the fan connector with AC set to high, and check for proper operation using jumper cables connected to the car's battery.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
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