5 Common Reasons Your Check Engine Light Came On

You’re driving down the road, drumming your fingers to your stereo as you receive an unwelcome surprise – the check engine light. There are several reasons your dashboard may be alerting you, and all of them aren’t also severe. Since the check engine light can come on for various reasons, it’s crucial to have a trusted automotive expert perform a troubleshoot to identify the exact cause. Staying informed can save you from unnecessary panic if the check engine light can be a quick fix. If your check engine light has recently come on, below are five commons reasons why: 

Bad Oxygen Sensor

The oxygen sensor plays a vital role in measuring the amount of unburned oxygen within your vehicle’s exhaust system. If you’re noticing that your car is guzzling more gas than usual, followed by the check engine light coming on, you should have the oxygen sensor inspected.

The Catalytic Converter is Failing 

The catalytic converter is an exhaust containing a crucial catalyst. The catalyst turns toxic gases into less harmful ones. A catalytic converter failing is usually not a standalone problem and usually is due to several other components that work interdependently, failing. 

Damaged Spark Plugs

Worn spark plugs are one of the most common reasons the check engine light comes on. The spark plugs ignite the fuel and air mixture within the combustion chamber to power your engine. While newer vehicles are less likely to experience problems, older cars with many miles may notice some issues if the spark plugs aren’t regularly checked. Over time the spark plugs can become worn and corroded, eventually leading to failure. 


Your vehicle’s engine has fast-moving parts that generate a lot of heat. It can overheat for a variety of issues, such as insufficient engine oil or a coolant leak. If your engine is overheating, you may notice smoke coming from under the hood and the temperature gauge reading high. If you suspect the engine is overheating, immediately pull over in a safe place until it cools completely down. 

The Gas Cap is Loose

It’s easy to forget the gas cap, but it serves an important role. The Gas cap keeps your fuel from evaporating and reduces emissions. It’s easy to leave the gas cap loose if you’re in a hurry at the gas station. If you tighten the gas cap and the check engine light doesn’t turn off, make sure the cap isn’t cracked or damaged. It may need to be replaced; however, gas caps are relatively inexpensive. 

Check engine light diagnosis in Brentwood, CA.

Monkey Wrenches Inc. has ASE Certified experts who offer full-service automotive repair to the Brentwood community. If you notice any of the above signs, don’t hesitate to reach out to us.

Click here to schedule an appointment or give us a call at 925-304-1291. 

Awards Image 1Awards Image 2Awards Image 3Awards Image 4Awards Image 5Awards Image 6Awards Image 7Awards Image 8Awards Image 9

Monkey Wrenches Inc. is committed to ensuring effective communication and digital accessibility to all users. We are continually improving the user experience for everyone, and apply the relevant accessibility standards to achieve these goals. We welcome your feedback. Please call Monkey Wrenches Inc. (925) 634-4145 if you have any issues in accessing any area of our website.