P0493: Cooling Fan Overspeed
What to do
Driveable. Expect a constantly roaring fan, a slower warm-up and a weaker heater in winter. Not urgent for the engine, but worth fixing.
What this code means
A fan is turning faster than commanded. On variable-speed fans the module both sets and monitors speed, and an overspeed reading means either the control has lost authority — a driver stuck on, or a relay welded closed — or the speed feedback is wrong.
A fan running at full speed continuously is the usual presentation. It is not dangerous to the engine, but it is loud, hard on the battery at idle, and slows warm-up in cold weather enough to affect economy and cabin heat.
Likely causes
Start here
- Failed cooling fan relay · easy
- Faulty fan speed control module · moderate
Less common
- Faulty fan speed feedback signal · moderate
- Signal wire shorted to ground · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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