The Check Engine light means the Engine Computer detected a problem, set a diagnostic fault code, and turned the light on to tell you. The place to start is by having that code read and recorded. The people at many auto parts stores will do that for you for free. A good suspect is low system voltage due to a charging system problem. Measure the battery voltage with the engine running. It should be between 13.75 and 14.75 volts. If that is okay, you need a professional load tester for the rest of the tests. That involves measuring full-load output current and "ripple" voltage.
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Saturday, December 5th, 2015 AT 5:53 AM