The Check Engine light is on, but the last mechanic could not get his machine to read the car, something to do with the connection.
You likely have a blown fuse which supplies voltage to the diagnostic connector. This will prevent the scan tool to connect to the engine computer. Most of the time GM likes to use the cigarette lighter fuse to supply the connector. Once the fuse issue is resolved, further diagnostics will require scanning of the codes. This will allow the mechanic to determine the cause of the Check Engine Light and make the necessary repairs for your car.
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