Car Fan Still On When Engine is Turned Off

You park your car, turn off the ignition, and walk away. Then you notice the engine cooling fan is still running even though the car is turned off. It is ok for the engine cooling fan to keep running for a few minutes after turning off the car. Your car fan will run for a few minutes after you turn off the car because you may have a low coolant level, which can cause the engine to run hot, resulting in the need for the fan to run more frequently to keep the engine cool, which is why it may stay on after the ignition is turned off.

This is normal in many vehicles, such as BMW or Mercedes-Benz. The radiator fan may run up to five minutes and sometimes longer. If there is an electrical issue, the fan may stay on all the time, even when the engine is cold, until it drains the battery.

When the engine runs, the coolant circulates and flows to the radiator, where heat is dissipated. When the engine is turned off, the coolant doesn’t circulate, and the heat stays trapped, preventing the engine from cooling. Running cooling fans help cool down the engine even after you turn off the car.

Why does the engine fan in my car stay on after I turn off the ignition?

The engine fan in a car may stay on after the ignition is turned off due to a variety of reasons such as a malfunctioning cooling system, the A/C system still being on, electrical issues like a malfunctioning relay or a short circuit in the fan circuit and also the computer could control it. Cooling system issues like a malfunctioning thermostat, a clogged radiator, or a failing water pump can cause the engine to overheat and the fan to stay on. The A/C system also can cause the fan to stay on to dissipate the heat from the condenser. Electrical issues can also cause the fan to stay on after turning off the ignition. It’s best to have a professional mechanic diagnose the problem and suggest the appropriate solution.

Common Causes

If your cooling fan runs for over 10 minutes after turning off the engine, you may have a problem that needs to be fixed.

Here are some possibilities causing the fan to stay running longer.

• low coolant level,
• faulty coolant temperature sensor,
• PCM or ECU defective
• coolant leaks from the water pump,
• cracked radiator,
• worn upper or lower radiator hoses,
• leaky heater core,
• leaky thermostat housing,
• rusted coolant bypass pipe,
• bad radiator fan relay,
• short in the electrical wires and so on.

Conclusion

Car fans staying on after the engine is turned off may be caused by several reasons, such as low coolant level, malfunctioning cooling system, still-on A/C system, electrical issues, or computer control. A low coolant level can cause the engine to run hot, resulting in the need for the fan to run more frequently to keep the engine cool. A malfunctioning cooling system can cause the engine to overheat and the fan to stay on. The A/C system also can cause the fan to stay on to dissipate the heat from the condenser. Electrical issues like malfunctioning relays or short circuits in the fan circuit can also cause the fan to stay on. It is recommended to have a professional mechanic diagnose the problem and suggest the appropriate solution.

Troubleshooting Tips

Test the fan relay; swap the bad one with a good one with the same pin design. Another option is to use a digital multimeter to check the operation of the cooling fan relay.

If the fan turns off, that means the relay is at fault.

Furthermore, check for low coolant levels and possible leaks that may be causing it. Usually, a low coolant will equate to a hotter engine. Therefore, it will activate the fan more often.

Frequently Asked Questions

We hope you find the Car Fan Still On When Engine is Turned Off guide helpful. Check these troubleshooting and repair guides for more help on your vehicle.