Why did you have to tow the car? How long has the Check Engine light been on? The Engine Computer detected a problem, set a diagnostic fault code in memory, and turned the light on to tell you that. The place to start is by having the code(s) read. Those will indicate the circuit or system with the problem. There are hundreds of potential causes and very few of them actually result in a running problem that you would notice. When there is a problem though, some of the self-tests will not be run by the computer so of course it will not pass an emissions test. Those self-tests take the place of what they used to have to do manually.
Have the fault code(s) read. Your mechanic will know from that how to proceed.
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Friday, November 9th, 2012 AT 9:05 PM