What Causes the “Check Engine” Light to Come On?

Many car owners know that if they want to keep their current car a trustworthy source of transportation, it is important to take care of their vehicle.  In spite of keeping up with routine engine service, when the “Check Engine” light starts to glow on their dash, anxiety starts to fill their mind.  What is happening under the hood?  And what causes the “check engine” light to come on? Their biggest fear is that a major engine repair could cost thousands of dollars.

Just remember that the “Check Engine” sensor is part of the on-board diagnostic system that is continuously monitoring engine performance, such as engine speed, air to fuel ratio, and ignition timing.  If a “fault” within the system is detected, whether big or small, the “check engine” light will illuminate.

So what causes the “Check Engine” light to come on?  Here are several of the main causes to consider:

1. Damaged Gas Cap – If the gas cap is loose, fuel vapors leak out and can throw the whole fuel system off, reducing gas mileage and increasing toxic emissions. Tightening or replacing the gas cap may resolve the issue.
2. Oxygen Sensor failure – The oxygen sensor monitors the unburned oxygen from the exhaust system, and how much fuel is burned. A faulty oxygen sensor doesn’t send the right data to the computer, which then reduces gas mileage and increases emissions.  
3. Catalytic Convertor Failure – The catalytic convertor reduces exhaust gases by converting carbon monoxide and other harmful materials into harmless compounds. If it fails, gas mileage wills reduction and loss of power when you try to accelerate. 
4. Faulty Mass Airflow Sensor – This sensor tells the car's computer to add the proper amount of fuel based on the air coming through to the engine. If the mass airflow sensor fails, toxic emission will increase, your car may stall, and gas mileage will decrease.
5. Dirty Spark Plugs and Wires – The spark plug provides a gap for a spark to jump across and initiates combustion in your engine.  If they are starting to go bad, replacing them is an easy fix

A word of advice:  Take care of recommended engine service items to help prevent small engine issues to turn into an expensive engine repair.  

Do you want to know more about what causes the “Check Engine” light to come on?  Contact our ASE Certified technicians at Proshop Automotive for more information about engine repair service and to make an appointment. Our auto repair shop proudly serves residents in Colton, CA, and the surrounding areas.