Why Does My Check Engine Light Come On?

It’s a situation most drivers know well but still fear–in the middle of a commute, the check engine light comes on. As a catch-all for engine irregularities, something has signaled your vehicle’s computer. And that tricky yellow light could mean almost anything, from minor to catastrophic. On the up side, on-board diagnostics in modern vehicles have made diagnosing engine maladies simpler than ever. You can troubleshoot yourself or trust a professional. Either way, neglecting an illuminated check engine light isn’t an option.

Understanding Trouble Codes

Carmakers have generated a list of codes (unique to their models) that signify specific issues. When a system notifies the computer that something is amiss, the computer saves these codes. Once you uncover a code, it will help you find the source of trouble.

Accessing Trouble Codes

There are several commercial scanners available at auto parts stores that can help you find your model’s problem codes. However, you can access them manually, as well. To get a code by hand, you’ll need a paperclip, pen and paper, jumping wires, and the owner’s manual.

  • Option 1 – To begin, turn the ignition a couple of times without starting the engine. When you’ve done this, ensure the key sits in the on position. This step tells the car to check for any saved codes. You will notice all the dashboard lights turning on and off before the service engine light comes on and stays on. After a few beats, this light will begin to blink. Now, focus and count the blinks. Each blink represents a number, a pause between blinks means a space between numbers, and a flashing light stands for 0. For example: pulse, pulse, pulse, pulse, pause, flashing light = 40. When you’ve found the code, write it down and reference the owner’s manual to find its meaning.
  • Option 2 – Play with the ignition just as Option 1 requires but press the Trip and Reset buttons on the odometer simultaneously. If you’ve done it correctly, the engine code should appear on the odometer.
  • Option 3 – Use the owner’s manual to locate the assembly line diagnostic lead. Although it might vary depending on your model, it can usually be found under the dash near the driver’s side. Next, complete step 1 per the first option, then connect the two A and B terminals using the jumping wire or paper clip. If you’ve done it properly, the check engine light will blink (like in Option 1). Count, record, and check the codes in the same way as the first method.

Although it might take some detective work, finding the problem codes is the first step to understanding what your engine needs. However, unless the problem is simple enough to handle at home (a loose gas cap can trigger the check engine light), consider having a professional mechanic do the heavy lifting. Also, if you have trouble accessing the codes, most shops have diagnostic equipment that can find codes in a few short minutes.

For all your car’s repair and maintenance needs, call the experts at Autobahn Automotive in Sea Girt, NJ, today!