The mechanical CEL fix. Is essentially two sparkplug antifoulers that are used to limit the amount of
oxegen your ECU sees so that it doesent throw a Check Engine Light when you put an aftermarket header on mine. I was in the process of doing that to my zetec when I put a header on. very easy. You will get a check engine light on. Only way to turn it off is to do the CEL fix or get a tune. Here ...