Check Engine Light 101

The check engine light, the idiot light, the light that means you can’t pass inspection. There is an old Texan saying: You are having a good day if you haven’t had to see your doctor, your lawyer, or your mechanic. Unfortunately, this light means you have to see your mechanic so your day just took a turn. The massive amount of things that can cause this light to come on often causes confusion or even frustration. Google is both a help and a hindrance on this count.

This light can be on for something as simple as a bad or loose gas cap. It can also point to major engine or transmission failure. All vehicles made after 1996 are equipped with an ODI II coder reader (onboard computer diagnostic system, version 2) that constantly monitors your vehicle’s major operating systems. The main purpose of monitoring these systems is to ensure that the vehicle is operating at top efficiency with the lowest possible emissions. As fuel economy and emission control have become increasingly important and complex, your vehicle’s electronics systems need to constantly adjust and fine-tune various parameters according to driving conditions. When the computer reads that any of these parameters do not fall within the acceptable range for operating the vehicle over a period of time, your check engine light comes on to warn you that you may have a serious problem. The real problem here is that this light does nothing more than let you know something is wrong. Many people head to their local auto parts retailer to see if they can be persuaded to pull the codes for free or resort to buying a scanner of their own to read the codes.

A common misconception is that the computer in the vehicle is smart enough to figure out what is wrong with the car. The modern smartphone is 100x smarter than the computer in your vehicle. The power control module can only do basic calculations that have not taken the place of a technician. There is no magical computer that a shop can hook up and tell us exactly what is wrong. Reading the codes from your car’s computer system gives us some symptoms to check, similar to when you go to a doctor and tell them that you have a cough, a runny nose, and a bad headache. This can mean you are having an allergy attack, a bad cold, the flu, or pneumonia. The same is with any proper automotive shop. Pulling the codes gives technicians an area to check as well as certain tests to run, which usually require additional tools and knowledge. Yes, sometimes the code does point to a sensor that turns out to be faulty; just as often the sensor is doing its job and has detected a problem that needs to be remedied.

Do not fear the check engine light, just know that it means your car needs a little attention. Just like with a doctors visit, do your research and find a good mechanic to guide you through the process. Use Google reviews, Yelp, friends, family, or even ask your local quick lube shop to help you find a good shop. A proper shop should take the time to guide you and explain what is going on. They should not just pull codes and shoot from the hip. They should treat your car like a doctor treats you; listen to the symptoms and run checks before pronouncing a diagnosis.

Author: Tanvir Suri – Owner/Operator

T&K Transmission & Automotive Specialists

Addison | Irving | Arlington TX