Why is the Check Engine Light on?

The little orange light. Why is it that the check engine light can evoke so much fear in car owners? Here we’ve provided information on some common check engine light issues, most of which are not serious, especially if quickly addressed as soon as the light comes on...

Loose or Broken Gas Cap

If the check engine light has come on in your car, the best thing that you can hope for is a loose gas cap. If the gas cap is loose, or if it has become cracked or busted, it may allow gas vapors to evaporate out of the filler hose, thus triggering the light. To avoid taking a trip to the auto repair shop for a problem that can be solved with the turn of a wrist, always be sure your gas cap is nice and snug every time you leave the gas station.

Malfunctioning MAF Sensor

The mass airflow sensor, or MAF Sensor, measures incoming air in order to calculate how much should be mixed with the gas to create a properly running engine. If the sensor fails, there is a good chance you will see a large drop in fuel efficiency as your vehicle begins to burn excessive gasoline. Many times the sensor only needs to be cleaned, not fully replaced.

Failed O₂ Sensor

The oxygen sensor works similar to the MAF sensor, but at the other end of the car. It monitors the exhaust for oxygen levels, helping to dictate how much gasoline is mixed with the incoming air. A failed oxygen sensor can also result in a major decrease of fuel economy.

Faulty Catalytic Converter

Damage to the catalytic converter is an example of a larger issue that can occur if the warning from check engine light is ignored. The catalytic converter is designed to transform hazardous exhaust fumes into less harmful emissions. If the catalytic converter has failed, it’s likely due to a smaller problem that would have triggered the check engine light first. The catalytic converter uses rare metals and can be quite expensive to replace, but it usually won’t fail on its own. Head to the shop as soon as the check engine light turns on in order to avoid expensive repairs.


The check engine light shouldn’t be something that scares us — it does us a favor by providing the opportunity to have small problems repaired before they turn into bigger issues. If you’re looking for check engine light diagnostics in Denton, bring your import or domestic car, truck, or SUV to Tommy’s Hi Tech Auto Repair. We offer auto repair at our modern facility, conducted by ASE Certified technicians.

To schedule expert auto repair in Denton give us a call at (940) 387-0070 today!

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