Your vehicle’s ignition switch turns your BMW on and starts the engine. Ignition switches come in an array of designs, but all function similarly. Whether your BMW uses a physical key that must be inserted into the ignition switch, a key fob with a chip that must be inserted into the ignition switch, or a key fob with a chip that simply needs to be in the vehicle, the ignition switch only allows your unique keys to turn on and start your vehicle.

Ignition switches fail in a multitude of ways. Physical failure of an ignition switch can include the tumbler becoming stuck or breaking free from the switch and being able to turn freely around in the switch. Physical failure can also include the pins in the tumbler wearing, preventing the key from turning the tumbler, and the connection between the tumbler and the electrical switch wearing and no longer making contact.

Electrical failures include an open circuit in the switch, a short to ground, worn electrical pins not connecting, and circuit or memory failure of the chip reader. Any component failures of an ignition switch will result in your BMW having difficulty starting or not starting at all.