It's our job to read your cars mind. There are over 250 reasons that your Check Engine light will come on, and that doesn't include possible problems with the transmission, antilock braking system, heating and air conditioning, safety-restraint system, or airbags! It's an arduous process. We start with hooking it up to our computer, but then we have to analyze the data the computer gives us to decipher whether the data is abnormal or not. Then we test the circuits, sensors, and wires that could be the problem. We also test-drive the car to experience the system, and again after repairs are made to be sure everything is in proper working order.