While the engine runs
Engine cooling fan will not stop: when it is normal and when not
It is normal for the fan to keep running for a few minutes after switching off a hot engine or after a particulate filter regeneration. If it always runs, runs at full speed even when cold or never stops, the control unit has gone into a fail-safe mode because of a sensor or fan fault.
Check without hurryWhile the engine runs
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Usually not urgent, but do not ignore it. It is not usually urgent, but have it checked: if the fan does not stop with the car off, it can drain the battery. If the temperature also climbs or the light comes on, stop and switch the engine off.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Normal run-on after switching off: cools the engine or turbo for a few minutes; on diesels, also after a regeneration.
- Coolant temperature sensor: if it fails, the control unit runs the fan at full speed to be safe.
- Fan relay or module: a stuck relay keeps the fan powered all the time.
- High A/C pressure: the system asks for airflow to bring the pressure down.
- An engine that really is overheating: low coolant or a stuck thermostat.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: What does the engine thermostat do and what does P0128 mean? What is a particulate filter and how long does a regeneration take?
Car system: Cooling
What you can check yourself
Note how long it keeps running after you switch off: a few minutes is normal, more than a quarter of an hour is not.
Check whether it also happens with a cold engine right after starting.
Look at the temperature gauge and at the coolant level with the engine cold.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
Related fault codes
- P0480Fan 1, control circuit: malfunction
- P0483Fan rationality check: malfunction
- P0117Engine coolant temperature sensor 1, circuit: signal low
- P0118Engine coolant temperature sensor 1, circuit: signal high
- P0217Engine coolant: over temperature
Generic codes that often come with this symptom. Seeing one does not confirm the cause: it is where the diagnosis starts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: coolant temperature (compared with the air temperature after a night parked), fan command and fan or temperature sensor codes.
Frequently asked questions
Why does the fan keep running after I switch the car off?
To cool the engine and turbo after hard use, or at the end of a particulate filter regeneration. It is normal if it lasts a few minutes.
Can it drain my battery?
Yes, if a relay or a module keeps it running for hours.
Can I disconnect it?
No: the engine could overheat. Fix the cause.
Keep reading
- Engine cooling: how it works and what fails
- Car overheats in traffic and cools down when moving: what is wrong
- Car battery keeps going flat: causes and what to do
- Particulate filter regenerating too often: causes
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means