Why is the check engine light on?

Why is the check engine light on?There are many ways that your vehicle may inform you of a problem, such as weird smells, vibrations or odd noises. However, one of the most obvious signs of trouble is if the check engine light comes on. While many people worry that this light indicates a massive failure, it often represents something relatively small. As long as it is addressed in a reasonable amount of time you won't have to worry about extensive repairs and expensive bill. But if you wait, you could end up with a big problem, such as the first in this list of common check engine light issues.

Failed catalytic converter

The catalytic converter is tasked with converting hazardous exhaust fumes into less harmful emissions. If it is not doing its job properly it will need to be replaced. This is unfortunately one of the most expensive parts to replace on any car or truck. However, it won't fail unless some other problem occurs first, such as a failed sensor, which would have triggered the check engine light long ago.

Malfunctioning MAF sensor

The mass air flow sensor is located in the front of the vehicle. It measures incoming air to calculate how much needs to be mixed with the gas for a proper running engine. If the sensor fails it will result in too much gasoline being used, which increases emissions and damages the catalytic converter.

Failed O2 sensor

The oxygen sensor is similar to the MAF sensor but it is located in the exhaust system. It measures oxygen in the exhaust to also help determine the proper air/fuel mix. If it malfunctions, or if there is an exhaust leak, again, too much gasoline will be used, thus lowering fuel economy and damaging the catalytic converter.


Misfiring is an issue you will likely notice with or without the check engine light. It means that one or more cylinders is not firing at the appropriate time. This will cause a rough idle and possibly stalling. Common causes include worn spark plugs or failed ignition coils.

Loose gas cap

Your best hope if the check engine light comes on is that you simply forgot to tighten the gas cap the last time you filled up. A loose or broken gas cap will allow fuel vapors to escape from the filler hose, meaning you're losing gas you didn't even get a chance to use.

If the check engine light comes on do not put off diagnostics. For professional check engine light repair in Mills, Casper or the surrounding Wyoming communities be sure to visit Chuck's Auto Repair Service. Our expert auto repair techs will get the issues figured out and repaired quickly and effectively. Give us a call at (307) 265-0209 to request more information or to schedule superior auto repair in Mills.

Chucks Auto Repair Blog

Written and Published By MORBiZ

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