Top 5 Reasons your Check Engine Light Turns On

January 21st, 2016 by

The check engine light is probably the most frustrating, rude, and untimely thing to pop up in life. No need to panic though, chances are it’s nothing pressing. You won’t need to make an emergency run over to a Chevy service department, but you still need to get it diagnosed and check out what’s going on. This is because the check engine light can pop up for a multitude of things, and unless the engine light pops accompanied by stalling, smoking, or strange sounds, it’s probably not a urgent issue.

Actually, the top 5 reasons the check engine light comes on are all an easy fix, and nothing immediately dangerous to your car. However, it’s still important to get it diagnosed relatively fast, that way you can get the problem taken care of. While it might not be an issue right now, some of the following reasons can cause serious damage over time if ignored.

O2 Sensor

The O2 (oxygen) sensor is a part under the hood that monitors the amount of unburned oxygen from the exhaust, along with how much fuel is burned. If your O2 sensor is faulty, it can cause an unnecessary amount of fuel to be burned, resulting in a reduction in fuel economy. Also, because they are attached to wires, you also need to check those as well.

This is because if a wire hits the exhaust manifold and the casing melts, it will short out the O2 sensor and shut off the car. This issue also causes your check engine light to pop on, and the engine to sputter and stall. I know this one from experience, and it was the most frustrating thing to try and diagnose. It was such a simple fix to a very unusual and unexpected issue. All I had to do was re-wrap the wire, and move it away from the manifold. Just another thing to watch out for if any of you are driving an older car…

Anyway, most cars have between two and four oxygen sensors, and there is a more common scenario as to why it causes the check engine light to pop on. Just like all other parts on a car, wear and tear over time takes its toll on the O2 sensor. The O2 sensor will eventually get covered in oil and ash, which reduces it’s ability to regulate the oxygen and fuel mixture.

If ignored, it can increase your car’s emissions output, as well as eventually cause damage to the spark plugs or catalytic converter. Thankfully, the O2 sensor is generally easy to spot and replace; all you need to do is find it, unclip it, and put in the new one. If that doesn’t turn off the check engine light, then it’s important to check this next infuriatingly simple cause…

Gas Cap Loose

You got a late start this morning, and when you get in your car after letting it warm up, you notice your fuel light is on. Great, so you will now be running even more late. You drive to the gas station, hastily pump your gas, hop back in your car, and drive away… but you forgot something.

There are three reasons why your check engine light pops on for your gas cap: it’s loose, damaged, or completely missing. Yes, you read that right. Your check engine light will pop on if your gas cap is loose. Imagine going through the trouble of getting your check engine light diagnosed, only to realize it was the gas cap the entire time? Infuriating, but not a major issue.

Why does this pop on when loose, damaged, or missing? Because harmful fuel vapors are released from the system if the cap is damaged or not tightened enough. Also, those leaking vapors aren’t just harmful emissions, they also throw the entire system off. Which causes a reduction in gas mileage.

Just like with the O2 sensor; if your car isn’t making any weird sounds or feel strange, check the gas cap. This should be the first thing to check, seeing as it’s the easiest fix. Make sure it isn’t cracked or loose, and if it isn’t you should get your car diagnosed, because it could be one of the remaining three issues that are a little more serious.

Catalytic Converter Needs to be Replaced

Another common issue that’s more pressing is your catalytic converter might be damaged. The catalytic converter is the go-green part of any car; it converts the carbon monoxide and other harmful emissions into harmless ones. If the catalytic converter is failing or damaged, you will notice a decrease in gas mileage, or you will be lacking acceleration when stepping on the gas pedal.

This is also a prime example of why regular maintenance is important, because the only way the catalytic converter can “fail” is if spark plugs or O2 sensors are not maintained and replaced. If you ignore it long enough, eventually the car will stop running completely. Also, your vehicle won’t pass an emissions test (if it’s new enough for that).

Mass Airflow Sensor Needs to be Replaced

The mass airflow sensor helps regulate the amount of airflow that comes through the engine, which then determines how much fuel needs to be used to run your engine efficiently and properly. Much like the O2 sensor, this MAF sensor can cause the check engine light to pop on for a simple reason. The sensor fails because of an incorrectly installed air filter, or lack of one.

This one isn’t as pressing as the catalytic converter that needs to be replaced, and you can actually run the vehicle for months with a broken MAF sensor. Is it advised though? No, because the first thing you will notice is a decrease in fuel mileage. Then, your car will eventually start stalling.

It’s interesting how a lot of these issues are all connected in some way, and they all affect the fuel efficiency of a vehicle. So, how does the last common issue connect with the others?

Spark Plugs/Wires Need to be Replaced

The spark plugs are a component of the vehicle that ignite the air/fuel mixture in the combustion chamber in the engine. Furthermore, the wires that run to the spark plugs provide the spark needed from the ignition coil so they can ignite and combust. If the spark plugs are failing, they will end up misfiring, throwing the combustion process off. Because of this, you will notice a change in performance and reduction in fuel efficiency. If ignored for too long, your engine will eventually stop running.

Getting your spark plugs changed is very simple, and it’s also part of your regular maintenance. Even if you haven’t been keeping up with regular service visits, it’s easy to change them out yourself. There are plenty of videos online, and it’s as simple as removing the old wire and spark plug, then putting the new one in. A simple fix when it first happens, but if ignored the damage done to the engine will not be so easy to fix.

Most of These Are Simple Fixes

The top five common causes are simple fixes; whether it can be done by you or not. The only two you might have trouble replacing are the mass air flow sensor and catalytic converter, both of which require some elbow-grease and know how to repair. If you don’t have that knowledge, it’s best to just get it fixed at a garage or service center.

While these common causes of your check engine light popping on might not be immediate problems, it’s still important to figure out why your check engine light popped on immediately. Depending on the code provided by the computer-test, it could be something you need to get fixed next week or right now. Regardless, it’s important to know that these are only the top five common reasons, and there are still many more serious issues that could cause the check engine light to pop on.