Is the Diesel Car Unable to Shut Off Due to a Malfunction?
2 Answers
Diesel car unable to shut off is not an issue of damaged vehicle components. When the key is turned to start a diesel car, it only drives the flywheel to rotate, causing the piston to compress and combust, thereby pushing the crankshaft into reciprocating motion. Unlike gasoline cars, which rely on the key to control spark plug ignition, diesel cars do not. Therefore, once the starter motor ignites the engine, the key no longer serves any function. Even if the key is turned off, the high-pressure fuel pump continues to supply fuel according to its cycle, unaffected by the key being turned off. Here is the solution: directly disconnect the fuel line switch. Since this mechanical fuel line switch may be located under the seat or on the lower left side of the steering wheel, depending on the vehicle's layout, its exact position cannot be specified universally.
It's indeed quite frightening when a diesel engine won't shut off. I've seen many similar cases, usually caused by a faulty shutdown solenoid valve which is responsible for cutting off the fuel supply. If it gets stuck or rusted, the fuel flow won't stop, and the engine keeps running. It could also be due to a malfunctioning fuel shutoff valve, short circuits or electrical leaks in the wiring, or disrupted ECU control signals. For example, during a recent repair, the owner had replaced the valve themselves but it didn't work—turns out the relay contacts were burnt out. Safety first: if this happens, immediately pull over, turn on hazard lights, try removing the key or reconnecting the battery. If that doesn't work, tow it to a professional shop. Never force it to keep running, as the engine could overheat and seize, wasting fuel too. Regular maintenance, including cleaning the valve body and checking the electrical circuits, can prevent such issues.
