August 11, 2022
Written by
Kate Rochat

5 Reasons Why Your Check Engline Light Is On

In the midst of peak summertime and road trip season, it’s important to remember that the more wear and tear on your vehicle, the faster its parts break down. With price increases at the pump reaching record highs in the U.S. in recent months, it’s necessary to keep up with routine car maintenance to reduce costs where you can. If the check engine light comes on and stays on, this is typically an indication of safety-related faults or emissions. Routine car maintenance is vital because it helps to ensure your safety on the road. For example, if your brakes aren’t working correctly, you could have a severe accident. By getting routine maintenance done on your car, you’re helping to keep yourself and others safe. 

Even for the most experienced car owners, some car issues can be hard to spot and fix without the help of a professional. At Curbee, we care about people and their cars. With the help of our expert Curbee crew members, we put together a handy list of common reasons to answer questions like, why is my check engine light on or what does a check engine light mean. 

Loose Fuel Cap 

A loose fuel cap is one of the most common causes of a flashing check engine light. Gas is fuel for cars, and the cap plays an integral role in ensuring all things are kept under the correct pressure. The engine cap prevents moisture and dirt from entering the tank and causing a decrease in vehicle efficiency. If your check engine light comes on after a fill at the tank, make sure the cap is twisted correctly and firmly – or not on your trunk. If the cap needs replacing, Amazon and other car manufacturer retailers have a slew of options starting at as low as $4. 

Electronic Powertrain Controls

Vehicles are large computerized devices with an array of sensors and modules that run powertrains. Any issues with these sensors, networks or modules can trigger a flashing check engine light.

Catalytic Converter

The catalytic converter heats up hydrocarbons and other emissions so that they turn into carbon dioxide and water vapor to help protect the environment. The converter usually does not fail on its own, and because of this simply replacing the converter or the oxygen sensors will not solve the problem, but a mechanic can help diagnose what might cause the failure. 

Oxygen Sensor Failure

The oxygen sensor sends data to the vehicle’s computer, which it uses to create the right mix of air and fuel to enter the engine’s cylinders. The check engine light may come on when the sensor fails or registers a problem with the fuel and air mix.

Ignition Coils/Spark Plugs

Another common reason your check engine light may come on is to warn drivers that it is time to replace spark plugs and/or ignition coils. According to DigitalTrends, ignition coils generate the electricity needed for spark plugs to ignite the fuel and air mix in the cylinders. Worn coils or fouled plugs can cause any number of issues, including engine misfire.


The check engine light can be finicky, and even after taking the necessary steps to fix a faulty issue or part and remain on. In this case, there are a few methods on how to reset your check engine light but two of the most common are as follows: 

  • OBD2 scanner: enables you to see what's wrong with your car, clear trouble codes, monitor data in real time, and much more
  • Disconnecting/reconnecting the battery: removing the positive and negative cables from their terminals, waiting 15-30 seconds and reconnecting. Unless you’re an advanced car owner or mechanic, we’d suggest leaving this up to the pros just to be safe

Depending on the make and model of a vehicle, a check engine light may require less urgency than a flashing check engine light. While it always helps to consult with the owner’s manual to help determine issues, automotive retail stores and or a Curbee mechanic can connect the car’s computer to diagnostic equipment that will issue a diagnostic trouble code (DTC) to serve as a starting point to address check engine light issues.

Want help figuring out why your check engine light is