What is the reason for the engine not turning off when the key is turned off?
3 Answers
The reason for the engine not turning off when the key is turned off varies depending on the situation: 1. For vehicles with AC ignition, it could be due to poor contact in the key switch or a disconnected ignition wire; 2. For vehicles with DC ignition, it could be because the key switch is damaged and fails to cut off power when turned off; 3. If the engine does not turn off after the key is removed but continues to rotate under the starter motor, it indicates a faulty starter relay. The functions of the car key include: 1. Vehicle locator function; 2. Closing windows after turning off the engine; 3. Opening windows; 4. Opening the trunk; 5. Unlocking only the driver's door.
This situation is really annoying. I've fixed quite a few cars with this issue. Usually it's caused by a faulty or stuck ignition switch, which prevents the engine from shutting off after cutting power. Some vehicles may have relay failures or ignition coil short circuits that send wrong signals to keep the engine running. Another common cause is poor wiring contact, especially in older cars with oxidized or loose connectors. Check the fuse box - if fuses are blown or have poor contact, the system can't shut down completely. Never force the car to keep driving as engine overheating can damage more components. Pull over immediately and try removing the key several times to see if it stops. If not, call a tow truck to the repair shop. Anyway, this concerns safety - the sooner it's fixed, the better.
I've encountered this issue several times. Last time when I was driving my friend's car, the engine kept running after turning off the key, which caused quite a panic. It's most likely an ignition system problem, such as worn key cylinder or dust blockage preventing complete circuit disconnection. Sometimes it's a faulty voltage regulator making the engine think it needs to keep running. If it's a diesel vehicle, check if it's stuck in the starting cycle. I recommend checking if the key is fully inserted and gently wiggling it to observe the response. Regular maintenance should include cleaning the ignition area to prevent such problems. Safety first - address this immediately when discovered, don't delay.
