It’s no fun to drive with the check engine light on your dash. Chances are, it’s nothing serious, but you can’t help but worry. What if your car stops running while you’re driving? Is it going to cost a lot to fix? Is it an emergency? Instead of panicking, take a deep breath, relax, and check to see if the following is the reason you’ve got the check engine light on.

1. Loose Gas Cap

It’s a fact that a gas cap, in its natural state, is not perfectly airtight. Over time, it’ll loosen and allow air to enter the tank. This can cause the fuel sensor to malfunction, and your car’s computer will sense that something is wrong. The check engine light will turn on, and you’ll have to tighten the gas cap. Don’t forget to check and tighten it every time you fuel up.

2. Faulty Oxygen Sensor

An oxygen sensor measures the amount of oxygen in the exhaust. If the reading is off, then this sensor is most likely the culprit. The sensor may need to be replaced, but more often than not, you can simply adjust it.

The O2 sensor is attached to the exhaust manifold in order to keep tabs on the amount of oxygen present in the exhaust gases. When the sensor is faulty, it’s no longer able to do its job. As a result, the computer will misread the signal, causing the check engine light to come on.

3. Catalytic Converter Failure

A catalytic converter is designed to work with the oxygen sensor. It’s designed to reduce harmful emissions, and it works by first burning the gas in a controlled environment. Since it’s working with the oxygen sensor, if there’s a problem with that, then the problem is likely to be with the converter.

Different catalytic converters have different ways of going bad. One of the most common issues is for the catalytic converter to be filled with too much gas. This causes the cat to not be able to convert the gas, which can lead to a cracked or broken converter. If you’re experiencing check engine light issues and you’ve just put in a new catalytic converter, then you may want to check the O2 sensor.

4. Damaged Spark Plugs or Wires

Car spark plugs are the ignition source for your vehicle. They have to be working correctly for your car to start and run. Your spark plugs can develop a short and cause the check engine light to turn on. To check your plug wires, find where the plug wires connect to the spark plugs. If the wires have a white or black coating, they’re okay. If they’re bare or have a green or blue coating, they should be replaced. It’s a good idea to replace all your plugs at the same time. 

5. Faulty Crankshaft Position Sensor (CPS)

Your car’s engine has a sensor that monitors how fast it’s spinning and at what RPMs. The scanner uses this information to run the car. If there’s a problem with the sensor, you’ll likely get a check engine light.

A faulty crank position sensor will cause the check engine light to come on. The easiest way to check if your CPS is the issue is to check the RPMs when your vehicle is running. If there’s a problem with the RPM, then it’s likely your CPS is the problem.


That’s a rundown of the most common problems that trigger a check engine light. It’s best to deal with these problems as soon as possible since a check engine light can turn out to be much more serious than you first think. If you notice your car’s check engine light coming on, don’t ignore it. Take your car to a mechanic as soon as you can. 

Don’t let minor car troubles persist for long, or you might end up with a more serious problem with your vehicle. It’s best to contact a professional mechanic in Hoover, AL, as soon as you can. Hoover Automotive is here to provide automotive services to our clients, from an oil change to repairs and part replacements. Our mechanics are highly skilled and experienced, so you can be sure that your vehicle is in safe hands. Call us today at (205) 509-3085 to schedule a service.

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