P0493: Cooling fan overspeed (clutch locked) — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
Fan overspeed is reported, with a locked fan clutch named in the definition. This concerns fan rotation and its coupling, not an electrically high control input. Confirm that this fan-clutch architecture is fitted before interpreting the monitor.
Affected system: Engine cooling fan control
Symptoms
- Warning light may illuminate
- Related system function may be impaired
- Vehicle-specific symptoms vary
Possible causes
- Mechanical timing or operating issue, sensor or actuator fault, connector or wiring damage
- Related wiring, connector, power or ground fault
- Vehicle-specific mechanical or control issue
What to check
- Record stored and pending codes and freeze-frame data
- Record freeze-frame conditions; compare relevant live data and inspect mechanical operation, wiring and related fault codes before replacing parts.
- Confirm measured values against the vehicle service information
- Retest under the conditions that set the code
- Record freeze-frame conditions; compare relevant live data and inspect mechanical operation, wiring and related fault codes before replacing parts.
- Repair the verified cause and confirm the code does not return
Also written as: P0493-00, P049300, PO493 (some scan tools add the fault-type byte, e.g. -00).