Cash for Clunkers

Tara Hornor
Written byTara HornorUpdated - October 19, 2023
Tara Hornor
Tara Hornor

Tara Hornor is an experienced writer and entrepreneur with over two decades of experien... | See full bio

Check Engine Light: Five Common Problems

Most cars today have warning lights and indicators on their dashboards, and a common and intimidating one is the CHECK ENGINE light. Depending on the problem, it could mean anything from a simple fix to something much more complicated and expensive. Thankfully, there are some straightforward steps to take to determine what your engine needs.

check engine light on

Check engine light help

Keep in mind that sometimes the check engine light will come on due to humidity and might turn off again on its own. But if it comes on and stays on, you’ll want to run a simple diagnostic test to determine the problem. Most automotive parts stores will run a free diagnostic and will be able to tell you within minutes the exact reason for the indicator light. Once you know which problem your engine has, you can then determine the steps to take.

Why does the check engine light indicator light up?

When getting a free diagnostic, the following are the five top problems that will show up for a check engine light indicator:

  1. Malfunctioning spark plugs and spark plug wires
  2. A loose, missing, and damaged gas cap
  3. A dysfunctional mass airflow sensor
  4. A malfunctioning O2 sensor
  5. A bad catalytic converter

check engine light on

Malfunctioning spark plugs and wires – A spark plug is the item responsible for the ignition of the air-fuel mixture and power for your car’s engine whilst the spark plug wires are the ones that are transferring the spark from the ignition coil to the spark plugs. A bad spark plug and spark plug wires is a common problem but one that will significantly affect the performance of your engine. Fortunately, it’s something that is easy to repair on your own. A clerk at a local automotive store would be able to help you pick out the right parts for your specific make and model.


Loose, missing, or damaged gas cap – According to experts, one of the silliest reasons to check on your CHECK ENGINE LIGHTS is damaged, missing, or loose gas caps. The function of the gas cap is to seal the fuel system, maintaining pressure and emission reduction. Thankfully, you should be able to simply replace a missing or damaged gas cap with the help of your local parts store.


Dysfunctional mass airflow sensor – Your mass airflow sensor is vital in determining the amount of air going into the engine. This then establishes how much fuel is needed to efficiently run the engine. If a free diagnostic shows that the MAS is the reason for the check engine light, you can either replace it yourself or take it to a professional mechanic. Just make sure to repair it soon. A bad MAS will compromise the internal combustion process and lead to major engine problems.


Malfunctioning oxygen sensor – The main purpose of the car’s oxygen sensor is to measure the amount of unburned oxygen within the exhaust system of the car. On top of the fact that it will cause the check engine light to be on, a bad or malfunctioning oxygen sensor will damage your spark plugs and affect your catalytic converter and overall fuel efficiency and economy. The best move for a driver without mechanical knowledge is to take the car to a mechanic shop for replacing the oxygen sensor.


Poor performing catalytic converter –The main job of a catalytic converter is to convert carbon monoxide into carbon dioxide. A poor catalytic converter will result in failed emission tests, high engine temperatures, poor engine performance, and inefficient fuel economy. A mechanic can determine whether the converter simply needs the blockage cleared out or completely replaced.

check engine light on

A diagnostic is key

There are various factors why the car’s check engine lights turns on and remains on. The first step is getting a free diagnostic from a local automotive store. From there, you can decide if the problem is something that you can repair yourself or if you need to take your car to an expert.

If you decide that the repairs are more than you are willing to do, then you can resolve whether to sell or junk your car for cash. To learn more about selling and junking your car for cash, visit





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