QuestionI have a 1995 Toyota Previa with 120,000 miles. One year ago my check engine light came on and the toyota dealership indicated that they could not specifically tell me what was making the light come on but several things could be checked (very vague and very costly). I had the O2 sensors replaced, both front and back. A month later I had the entire exhaust from the manifold to just before the second convertor. My check engine light went off and was off from September to January. It is now back on and again no one can tell me for sure what the problem is. How many problems can the check engine light indicate?
AnswerHello Joan, welcome to my expert page.
The check engine light can indicate a lot of different problems, most of them are related to emission control component failures, the light is turned on when the computer"sees" a problem form one of it's input sensors, it has built in parameters in the ROM, if it sees a variation above or below certain parameters it will turn on the check engine light, so much for the technical part.
In order for me to help you I need to know what the trouble codes are that are stored in the computer, your repair orders from the dealer should tell you this information, and you are correct, they seem a little vague, there is no mistery, the codes are retreived using OBD(on board diagnostic)tool and read from the display,all I need to know is what they are.
