Fan Secondary Low Speed Circuit Malfunction (Ford)
What does P1473 mean?
The P1473 code means the vehicle's onboard diagnostic system has detected: Fan Secondary Low Speed Circuit Malfunction (Ford). This is a moderate severity code.
Common Symptoms
- Engine overheating at idle or low speeds
- Cooling fan runs only at high speed
- Check Engine Light illuminated
- AC performance degraded
- Temperature gauge climbs in stop-and-go traffic
Probable Causes (Ranked by Likelihood)
- Failed low-speed fan relay Very High
- Blown low-speed fan resistor or module High
- Damaged wiring to the fan speed control circuit Moderate
- Faulty cooling fan motor (low-speed winding) Moderate
- PCM output driver failure Low
Step-by-Step Diagnostic Procedure
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Check the low-speed fan relay in the fuse box. Swap with an identical relay and test fan operation.
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Locate the fan resistor or speed control module and test for proper resistance values.
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Test the fan motor by applying 12V to the low-speed terminal. If it does not run on low, the motor is faulty.
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Inspect wiring between the relay, resistor, and fan motor for damage, corrosion, or breaks.
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Use a scan tool to command the fan to low speed and verify the PCM output signal is present.
Frequently Asked Questions
Why does only the low-speed fan fail?
Low-speed fan operation uses a resistor or relay to reduce the voltage to the motor. These components handle constant current and heat, making them more prone to failure than the high-speed circuit.
Can I drive without the low-speed fan?
For short distances at highway speeds, yes. At idle or in slow traffic the engine can overheat since the high-speed fan only kicks on at higher temperatures. Monitor your temperature gauge closely.
Is the fan relay the same as the AC relay?
No, though they may look identical and be located next to each other in the fuse box. The fan relay controls the cooling fan while the AC relay controls the compressor clutch. Always verify relay position from the fuse box diagram.