When thinking of the ignition in a car, you'll probably think of the slot you put the key into to start the car, but that's only a part of the ignition system, known as the ignition lock cylinder, which is the first stage of the ignition process.

Once the key has been turned, or the start/stop button has been pressed in some cars, the ignition switch will decode any anti-theft measures (such as the immobiliser) before allowing the vehicle to start.

In petrol cars, the ignition system's job is to take power from the battery and turn it into a spark that is powerful enough to ignite the vapour from the fuel to get the engine running.

Glow plug symbol in dashboard

Engines in diesel cars ignite the fuel using compression so no sparks are needed, but use glow plugs which heat the combustion chamber.

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