Powertrain
generic / SAE
P0493
Fan Overspeed
The cooling fan is rotating faster than the commanded speed. The control unit measures the fan tachometer feedback against the requested duty cycle and finds it well above the expected band - typically a stuck-open relay, a shorted PWM line driving the fan to full power, or a feedback line that misreports speed.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 93
Possible causes
- Fan relay welded closed - fan runs uncontrolled high
- PWM line shorted to supply medium
- Tachometer feedback miscalibrated low
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 80–400 €
- Estimated time: 0.6–1.8 h
- Component: cooling fan
- Component: fan relay
- Component: fan speed sensor
- MIL / check engine light
Sources
References
sae:J2012