Check Engine Light On problems of the 1998 Mazda Protege

Numerous problems with 1999 Mazda Protege lx. Days after the vehicle was purchased the check engine light illuminated while driving. The vehicle was taken back to the dealer where she was told that they were not very knowledgeable about Mazda because they were primarily a Honda dealer. The vehicle was taken to a service station where they suggested the problem had something to do with the gas. The technician reset the computer and told the consumer if the problem recurred to take the vehicle to a Mazda dealer. The check engine light continued to illuminate, but every time the consumer attempted to take the vehicle to be serviced the light would go off. Over the coarse of a few months the dealer replaced several components that they thought would alleviate the problem, but they didn't. It was later determined that the drain plug was not put back properly and fell out while driving.