What to Do When the Engine Delays Shutting Off After Turning Off the Key?

[LaAmy]

If the engine delays shutting off after turning off the key, it is recommended to check the following: 1. Carbon deposits on various components: Especially inside the cylinder, such as whether the spark plugs have excessive carbon buildup or if the combustion chamber has too much carbon. Since the engine operates at high temperatures, the carbon deposits inside the cylinder can remain hot and ignite the air-fuel mixture even after the spark plugs are deactivated (when the ignition is turned off). 2. Throttle: Check if it is not closing properly. 3. Fuel injector: Inspect whether the fuel injector is leaking. Precautions for using a car engine are as follows: 1. Avoid driving in neutral: The engine itself has a fuel-cut function during deceleration, and driving in neutral can actually reduce fuel efficiency. 2. Pay attention to observations: If oil is found on the ground, determine whether it is due to engine oil leakage and promptly communicate with the car dealership to eliminate potential safety hazards. 3. When brake fluid is contaminated with or absorbs water: Or if impurities or sediments are found in the brake fluid, it should be replaced or carefully filtered immediately. Otherwise, it may lead to insufficient braking pressure, affecting braking performance.

[VanAlessandra]

When my car's engine delayed shutting off, I immediately thought of common causes. Modern vehicles, especially turbocharged models, are designed with delayed fan operation for cooling purposes, which is a normal design feature. However, if this isn't the case, it could be an electrical issue such as a stuck relay or a faulty sensor preventing the engine from stopping immediately. I suggest first observing the symptoms: Is the fan running after shutdown? If there's no fan noise, check if the dashboard lights are on to rule out the engine not shutting off completely. For a quick check: After turning off the ignition, wait for 5 minutes. If it still doesn't stop, avoid forcibly opening the hood to prevent danger. Simply inspect whether the headlight fuse in the fuse box is blown, as this can sometimes cause a false running state. Promptly visit a repair shop to diagnose the ECU wiring harness or replace a failed relay. Regular maintenance can prevent this issue, especially not overlooking battery aging which may cause abnormal operation.

[CamillaFitz]

After turning off the key, the engine continues to run briefly. Common causes include the cooling fan operating—especially in turbocharged vehicles designed for extended cooling. If not, check the electronic system, such as accidental ECU module triggering or wiring harness short circuits. Inspection steps: Listen to the engine after shutdown—it should stop instantly. If it continues running, avoid driving—overheating may damage components. Temporarily remove a fuse to cut power (avoid frequent use to prevent damage). Recall recent modifications that might cause interference. If unmodified, likely a relay or fan motor failure—professional tools are needed to diagnose voltage/current. Regularly replacing old relays prevents failures. Avoid delaying repairs to prevent costly system-wide damage.

[VanBrooklyn]

After turning off the key, the engine continues to run with a delay. First, check common causes: whether the cooling fan is responding to cooling demands and continues to operate—if normal, there's no need to worry. If not due to this, check if the battery voltage is normal or if a sensor, such as a temperature probe, is faulty, causing a false start condition. Immediate action: safety first, do not turn the key back on; observe from outside the car for 5 minutes. If it doesn't stop, use an emergency tow or seek help from a repair shop. Check if the relay is stuck or if there's a fan issue. For DIY, you can check for blown fuses but avoid disassembling randomly to prevent electric shock. For prevention, inspect the electrical system every six months to maintain good condition.

[Charles]

When I notice the engine still running after turning off the ignition, my first priority is to check the design features: it's normal for many new cars, especially those with turbochargers, to have a delayed fan operation. However, if it's a malfunction, it might be caused by a stuck fan relay or an ECU logic error leading to delayed shutdown. For a DIY attempt: first, turn off the key and check if the fan is running; if it is, it's normal, if not, pull the relevant fuse in the fuse box for a moment to reset the system—sometimes this can temporarily solve the issue, but don't rely on it to avoid further damage. Professional issues like sensor failures require a visit to the shop for diagnosis; for routine maintenance, regularly clean the relay socket to prevent dust accumulation that can cause sticking. Ensure driving safety by addressing faults promptly to avoid unexpected risks.