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Why is the Check Engine Light On?

Why is the Check Engine Light On?Your car is equipped with numerous sensors and microprocessors that monitor how well your vehicle is performing in terms of efficiency, power and other safety aspects. If one of these computers determines your car is not performing as designed it can trigger a dashboard warning light, such as the check engine light. In many cases, this light illuminates due to a relatively small problem, but if left unchecked, that issue can grow much bigger, as demonstrated by this first check engine light problem.

Catalytic Converter

One of the most expensive parts to replace on a car is the catalytic converter. This exhaust system component is designed to convert hazardous exhaust fumes into less harmful emissions. It is very difficult to damage this part, and if it is found it is no longer functioning as designed when running check engine light diagnostics, it's likely the light has been on for some time. Putting off check engine light diagnostics will almost always result in a need for more expensive repairs than originally necessary. Let's explore a few other common check engine light triggers.

MAF Sensor

The mass airflow sensor measures the quantities of incoming air in order to determine how much of it needs to be mixed with the gasoline to create the proper air/fuel mix for the engine. If it malfunctions it will result in excessive gasoline being burnt, which will reduce fuel efficiency and create fumes that are damaging to the catalytic converter.

O2 Sensor

The oxygen sensor measures the amount of oxygen in the exhaust. This also helps calculate the proper air/fuel mix. A malfunctioning o2 sensor can also result in excess gas being used and cause the engine to perform poorly.


Misfiring is something you will likely notice on your own, even without the help of the light. Misfiring is characterized by an engine that runs very rough at idle or while driving. Misfiring is often caused by faulty spark plugs or ignition coils.

Loose Gas Cap

A best case scenario when running check engine light diagnostics is finding out that the gas cap is loose. If the cap is not secure it may allow fuel vapors to escape out of the filler hose, causing them to evaporate before you ever get a chance to burn them in the engine. Thankfully, the EVAP system will detect this issue and trigger the check engine light.

If your check engine light has come on, don't hesitate to have diagnostics completed. If you need check engine light repair in Watauga, TX, reach out to Kwik Kar. We provide full service auto repair for all makes and models! To learn more, or to schedule superior auto repair in Watauga, give us a call at (817) 519-8512 today.

Kwik Kar Lube & Tune of Watauga Blog
Posted: 05-10-2020

Written and Published By MORBiZ