The ignition coil on your Seat Leon is responible for turning the batteries low voltage into high voltage to enable the spark plug to create a strong spark to ignite the fuel. When a coil pack breaks down you will experiance a misfire meaning that the car may be running on one cylinder less. Its important to get this rectified at the earliest possible time to get the car performing at its best again. Check out the best quality ignition coils at orangespanner.