Skip the auto shop - Our mechanics make house calls

Q: Sounds like a small fan on engine when car off, not radiator fans.

asked by on

When I turn the engine off, a small fan stays on, causing the battery to die. But it's not the radiator fans. I've switched relays of similar kind for the fans and AC and it still stays on.

My car has 167000 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. The noise you ar...

Hi, thanks for writing in. The noise you are hearing is the emission control system performing a system test of the fuel tank vapor system. The system should run the test in less than ten minutes. If the battery cannot last long enough to finish the test before it dies then the battery may be bad and cannot handle the load and needs replaced. Have the battery tested to make sure it is not bad. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Lightning bolt

Hi There, The lightning bolt symbol relates to the throttle body control system. Current too high / too low is usually what the readout will indicate upon scanning the system for the fault code. There could be carbon build-up in...

Q: New battery; car won't start

Hello. If the car is not starting after a battery replacement then you either have a bad connection at the battery or it is possible that the programming in the computer got corrupted when the voltage was lost. This can...

Q: Coolant doesn't circulate and is leaking into coolant tank

Hello. If the coolant only leaks when the engine is running, then it is typically a failing water pump. This is the most common thing to leak under these conditions. The water pump should be checked for signs of leakage...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...