* Faulty ignition switch: The ignition switch is responsible for sending power to the engine when the key is turned. If the ignition switch is faulty, it may not be able to properly shut off the engine, causing it to continue running even after the key is removed.
* Stuck fuel injector: A stuck fuel injector can cause the engine to continue running even after the key is removed. This is because the fuel injector will continue to spray fuel into the engine, even when the ignition is turned off.
* Vacuum leak: A vacuum leak can cause the engine to run lean, which can lead to stalling. If the vacuum leak is large enough, it can cause the engine to stall even when the key is removed.
If your Mercedes 1981 300D is turning off even when the key is removed, it is important to have it inspected by a qualified mechanic to determine the cause of the problem.
