Best to get a diagnostic done in the garage, it'll come up with a fault code, but the light may go off before you get it there only for it to come on again.
What car is it? Mine is an Astra SXi and had to have an ignition pack (also known as a coil pack) and it has to be a Vauxhall part rather than a cheaper option which I tried 3 different ones until the Vauxhall one worked! grrr
fauxvaux, April 2010
