Anyone who has driven a car and had the "check engine" light come on understands the sinking feeling of, what do I do now?

What does it mean when that light comes on; should you check to see if your engine is still there, has it blown up, WHAT?

OK, take a deep breath and don’t allow panic to set in. First, take notice if there is anything different in the way your car is running. Does it feel rough, sluggish or jerky? If so, there may be a misfire occurring or a problem with the transmission and you will want to minimize driving.

An appointment should be made with your repair shop as soon as possible. If there is no change in how the vehicle is driving, the concern may be related to the emissions systems on the vehicle and you are OK to drive until you can make an appointment. On average, there are 80 to 110 reasons a check engine light can come on.

There is no way to know what caused the light to come on without running a diagnostic scan and performing the necessary testing to determine the cause of the fault. If the light came on after recently filling the gas tank, check to ensure that the gas cap is on and tight. A loose cap can set a code that triggers the check engine light. If the light is still on two to three trips after re-tightening the cap, the cap was not the cause of the concern.

On board diagnostic systems are quite complex and require expertise as well as special tools to correctly diagnose. Unfortunately, there is no super computer that can be plugged in and immediately give the answer to what is wrong.

There are computers that do provide the technician with information about what system is malfunctioning. From there, the technician will need to perform further testing to determine why that specific system is not operating correctly. Once the technician has obtained the fault codes, he/she can refer to a diagnostic chart or, "fault tree" that gives him/her the step by step checks that need to be performed. An intermittent fault can be difficult to track down and may require repeated attempts to repair.

To help the technician track down the concern as efficiently as possible, make a mental note of the conditions when the light came on: Was the car accelerating or slowing down? At what speed were you driving? Did you notice anything different about how the car was running, and so on?

If there has been any other work performed recently, let the service advisor know about that. Did the light come on first thing when the car started up or later while driving?

Remember, both you and the repair shop have the same goal, to get you and your car back on the road as quickly as possible.

Hopefully, I have helped shed some light on the mysterious check engine light and assured you not to panic, just give us a call and we will be happy to help get your car back into tip top shape.

Questions? Post comments here or contact Ridge McCoy, service manager at Alki Auto Repair, at ridgealkiauto@comcast.net or 935-8059.