What is the reason for the engine not turning off when the key is turned off?

[Haymitch]

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.

[OLeonardo]

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.

[LeLeah]

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.

[VanLeonardo]

This issue is quite common, mostly stemming from ignition switch failure or circuit short circuits. The engine not shutting down properly not only wastes fuel but may also cause overheating damage. The inspection method is simple: after parking, don't move the key and observe if the fan is still running; if it is, it indicates the relay might be stuck. Some new cars with complex electronic systems may experience occasional malfunctions. Quickly turn off the engine and pull over to avoid risks from prolonged operation. For daily car use, remember to regularly clean the keyhole and maintain the ignition system—small preventions can save major troubles.

[VonEzra]

I've seen this situation many times when driving old cars, especially with old-fashioned ignition systems. The engine not turning off when the key is removed is often due to burned contacts or aging springs, which fail to completely cut off the power supply. Circuit corrosion also frequently causes similar issues. I once drove a model from the 1990s where I had to manually pull the fuse every time to stop the engine. It's recommended to immediately check whether the relays and connecting wires are secure. Don't ignore this, as such faults can spread to other components and affect overall operational efficiency. Regular maintenance can help avoid these problems.

[DiKevin]

As someone who frequently drives long distances, I pay close attention to such issues. The engine not turning off when the key is removed usually indicates an abnormal ignition module or a worn-out key switch. It could also be caused by poor grounding forming a circuit that continues to supply current to the engine. If the car has modified circuits, check for compatibility issues. The first step should be to release the throttle and coast to a stop, then inspect the fuses and plugs. Avoid rushing to drive home to prevent engine damage and increased repair costs. Developing a habit of checking the dashboard before starting can help detect problems early.