5 Reasons Your Check Engine Light Might Be On

You are driving down the road and all of a sudden you hear it, “ding, ding, ding, ding”. Panic sets in as you look down and see that your check engine light is on. Your mind races as you try and figure out the issue (and how much it’s going to cost to fix it).

There are many reasons why your check engine might be on, but here are the five most common:

1. A loose, broken, or missing gas cap

The gas cap seals the fuel system and maintains pressure within the fuel tank. However, if your vehicle has a loose, cracked, or faulty gas cap, that seal is broken. Fuel can evaporate through a broken seal, which disrupts the exhaust system, thus cueing the check engine light.

Luckily, this problem can be easily fixed. First, ensure your gas cap is tightly secured. If this triggered the warning, the check engine light should turn off after you drive for about 10-20 miles. If the cap is missing or cracked, you can purchase a new one at an auto parts store for about $3.

2. Faulty spark plugs

Engines don’t just run on gasoline, they also need electricity, and that’s where spark plugs come in. According to YourMechanic, “Spark plugs connect to wires that lead to the ignition system. Electricity is created by the alternator and sent to the plugs, which create arcs of electricity. This is what ignites the fuel in your engine’s cylinders, creating the combustion that pushes the pistons down and actually turns the engine.”

When spark plugs fail, they misfire and you’ll feel a jolt in the vehicle’s acceleration. This may trigger the check engine light. Replacing spark plugs is relatively cheap, and it greatly improves your vehicle’s performance and gas mileage.

3. A malfunctioning oxygen sensor

Oxygen sensors measure the amount of unburned oxygen (and burned fuel) in your vehicle’s exhaust system. The sensor sends information to the vehicle’s computer, which regulates the combination of air and fuel that enters the cylinders. Over time, oil ash covers the sensor, causing the sensor to fail and trigger the check engine light.

While your vehicle will continue running with a dirty oxygen sensor, it will burn more fuel than usual. If you wait too long before replacing the sensor, crucial engine components can deteriorate.

Most cars have two to four oxygen sensors with their own unique codes. The codes tell the mechanic which one needs replacing. The repair costs depend on the type of vehicle you drive.

4. A defective MAF (Mass Airflow Sensor)

The mass airflow sensor measures the amount of air entering the engine. Its reading helps determine how much fuel is needed to efficiently run the engine. In addition to triggering the check engine light, some other signs your MAF sensor isn’t working properly working include:

  • decreased gas mileage
  • rough idle
  • trouble starting
  • engine stalling

Most MAF sensors fail because an air filter needs to be replaced, or a filter wasn’t installed properly the last time it was replaced. Air filters should be replaced once a year to prevent sensor failure and other engine-related issues (like damage to spark plugs, oxygen sensors, or the catalytic converter).

5. A failing catalytic converter

The catalytic converter is one of the parts in your vehicle’s exhaust system that converts the carbon monoxide generated during the combustion process into less harmful compounds. If your catalytic converter fails, you’ll notice decreased acceleration and poorer gas mileage. This issue can trigger the check engine light in more serious instances.

You can prevent catalytic converter failure with regular vehicle maintenance. Unfortunately, if your check engine light is triggered from a catalytic converter failure, it can be expensive to fix. So, if your check engine light does come on, get it checked ASAP. An issue left unchecked can lead to permanent vehicle damage.

If your check engine light comes on often or if vehicle repairs are becoming more expensive,  it may be time to get a new, more reliable vehicle. At Car City, we have a large selection of reliable vehicles to choose from with easy financing. Contact Car

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