When that sort of warning light comes on it stays on until the copmuter is reset. I don't know if this is done when the diognostic is done or not. My mechanic told me today that you can do it by disconecting the battery for about 20 min, but check with your dealer first!!!!

If the light doesn't come back on after the battery has been reconected than you may of just had a minor problem that fixed itself and the light stayed on until the computer was reset.

If the light does come on don't ignore it as it's on for a reason. If the engine is fine then it could be a faulty conection somewhere and you will need to go and check the wiring. I recomend getting someone who knows what they are doing to do this because if you touch the wrong wire you could inadvertantly set off the air bags

If you choose to ignore it then you run the risk of one day having sonething realy go wrong in the engine and not knowing about it until it's to late.