I am planning on selling my 2002 Mercury Sable this weekend (maybe not now) and the check engine light recently lit up. I know this could mean hundreds of different things, but I thought I would give some details and see if anyone had any theories. The car has 45,000 miles on it and there have never been problems with the engine in the past. The weather has just started getting cold where I live, around 20-30 degrees. I do drive the car at excessive speeds on a fairly regular basis, which I fear could likely be the cause of this light because this car is obviously not meant to be driven this fast. Any help would be appreciated!