GMC Check Engine Light – What are the General Causes?

If you have a GMC car and if you are curious about why the check engine light is on your dashboard, you are at the right place. We will explain all the important details about the GMC check engine light. You will be informed about the general causes. Also, you can find detailed information about the general solutions. If you are curious about how to solve that problem, we will explain you here.

Why My GMC Check Engine Light is On?

GMC logo.

There are different kinds of causes for this problem. And you can find the different causes of this problem that you can solve.

Problems with Spark Plugs and Electrical System

The electrical system of a car is very important. Because there are lots of electrical systems that help to start and run the engine. One of these systems is the spark plugs and ignition system. Spark plugs are responsible for the ignition of the air-fuel mixture inside the cylinders. And if they are not working well, the fuel will not burn and the cylinder will not produce power.

Also, each cylinder has its spark plugs. And if there is a problem with one of these spark lugs, you will feel an engine performance loss in your car.
And also if all the spark plugs are not working at the same time the engine will not work. Probably there is a problem with the distributor system that provides electricity to spark plugs at the right time. And we can understand that there is no electricity supply to spark plugs.

Another problem that we can face with the problem of cables. If the connection cables are problematic, the systems will not work properly.

How to Fix These Problems?

We can fix these problems in different ways. First of all, we need to understand the root cause of the problem. If there is a problem with an individual spark plug, we need to change it to a new one. Or, if the cause o the problem is carbon buildup on the spark plugs, we can clean it by applying the instructions of the cleaners.

One piece of GMS spark plug generally ranges between $20-$25. And replacement cost for labor is generally $25-$30. So, you need to pay around $60-$100 for one spark plug.

Also if there is a problem with the distributor of your GMS car, you can find OEM parts are around $75-$100. Also, the replacement cost of labor will be around $100. So, you need to pay around $200 for the replacement.

And if there is a problem with the connecting cables, you need to change them with new ones. And the general costs will be around $50 per cable change.

Problems with Oxygen Sensor

Also, faulty or problematic oxygen sensors can cause the GMC to check the engine light. The oxygen sensor must provide information about the amount of oxygen in the exhaust fumes to the ECU system according to the amount of oxygen, the ECU adjusts the fuel level in the air-fuel mixture in the cylinders. An optimum mixture is created for the optimum working of the engine.

So if the oxygen sensor will not work, the ECU system can not adjust the optimum fuel value for the engine. You will feel it as engine stall, misfires, and performance loss.

How to Solve?

The general reason for this problem lies in different aspects. The oxygen sensor has cable connections between the battery for power and the ECU system to transmit information. So, if there is a problem with these cables, they need to change to a new one. And replacement one cable cost is generally $50.

Also if you have a problem with the oxygen sensor itself, the cause of the problem can be carbon buildup. And because of this, the sensor could not read the exact value of oxygen inside the exhaust fumes.

The place of oxygen sensor is at the bottom of the car. And right after the catalytic converter, you can see the oxygen sensor is attached. It is attached with very basic wrench or screwdriver fasteners. So, you can easily rip it off. and clean the carbon buildup with proper solutions by complying with the instructions of these solutions.

To do it, you need to lift the car with a proper hydraulic or mechanical jack system. After that, you need to rip the fasteners. And then take the cables.

After the cleaning attach the cables and fasteners. And control the check engine light if it is gone or not.

Also, the problem can be the faulty oxygen sensor. The price of the OEM oxygen sensors varies between $150-$200. And also the replacement cost for the oxygen sensor can cost around $100. So if you want to change the oxygen sensor with a new one, you need to pay around $300.

Mass Air Flow Sensor Problems

You can see the GMC check engine light if you have a problematic mass air flow sensor. The mass air flow sensor in GMC cars must measure the total mass airflow to the intake manifold. And with the information of mass airflow and the oxygen from the oxygen sensor, the ECU adjusts the best level of fuel to the engine cylinders.

So if there is a problem with this sensor, you will feel the same symptoms as the faulty oxygen sensor. Also, the root cause of the problem can be the same as the faulty oxygen sensor.

Fixing MAF Sensor

Unlike the oxygen sensor, you can not fix the faulty MAF sensor on your own. The general price to change the MAF sensor with another one is generally the same as the oxygen sensor.

Also, all the fixing ways are the same as the oxygen sensor.

Loose Gas Cap

Also, a loose gas cap can be a problematic issue that makes the GMC check engine light on. To solve this problem, you just need to squeeze the gas cap in place. And the check engine light will off.

We can give you a joke idea about it 🙂 If your relatives or loved ones have GMC cars, you can untşghten the gas capo to make the check engine light on. And once the owner runs the engine, he or she will see that the check engine light is on. And hear she will be shocked 🙂 But do not hold the joke for too long 🙂

Aftermarket Items

Do not forget that the aftermarket items will not work properly with the other parts. So, this makes the GMC check engine light on. Once you bring your car to a GMC service, they will find out that the problem is the aftermarket part.

And once they change them with OEM parts, the check engine light goes off. So, it is very important to use OEM parts. We know that the aftermarket parts are cheaper than the OEM parts. But in general, they will not show the same performance as the OEM parts.

Problems with Catalytic Converter

Also, the most common problem that you can face is the problem with the catalytic converter of your GMC car. The catalytic converter must reduce bad exhaust emissions to lower and acceptable levels. So, it is very important for human health and the environment.

In general, catalytic converters of GMC cars have the problem of damaged or clogged channels.

If the catalytic converter is damaged, you will hear a strange sound coming from your exhaust.

Fixing Catalytic Converter

If the problem of your catalytic converter is damaged, the service will replace it with a new one. The catalytic converters can get damaged from the bottom of the car. In general, the OEM catalytic converters are $150-$200. Also, the total price of the workmanship will be around $100.

Also if you are familiar with the car mechanics, you can replace the catalytic converter on your own. It is a very basic process. The place of catalytic converter is at the bottom side of your car. If you follow the tailpipe, at the bottom of your car, you will see a semicylindrical part. This is a large catalytic converter.

In general catalytic converters are attached with very basic fasteners. If you have a regular wrench or screwdriver set, you can easily rip off it.
Before doing it you need to lift the car with a proper hydraulic jack. Also do not forget to take important safety precautions such as protective glasses and gloves.

Also if the catalytic converter is clogged, you will feel this problem as the power loss in your engine. This is because the engine gives more power to expel the exhaust gasses from these narrow channels. You can clean the catalytic converters with proper solutions.

Cost of GMC Check Engine Light Diagnosis

GMC Check Engine Light

We always recommend that you need to bring your GMC car to a service if you see a GMC check engine light. They are using a special tool to check the exact problem. They are attaching a device to the ECU system of the car.ç And the device shows the cause of the problem immediately. So it is very important to experts must diagnose the situation.
The general diagnosis prices range between $50-$75.

Last Words on GMC Check Engine Light

As you understand from above, it is very important to consider the GMC check engine light correctly. We explained the general solutions to the problems that you are facing. And also we give different kinds of directions to you to consider the different kinds of things.

If you have additional comments and questions about this issue, please leave them below. Your precious feedbacks are very important to us.


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Uğur Uygun

Hello everyone, I am Uğur. I am a mechanical engineer who has experience in different R&D departments of HVAC companies. With my best friend, I decided to build this website to share out knowledge and experience. And also, I am interested in automotive. So, I am writing about automotive and automotive-related articles here. Sharing my knowledge and experiences on these topics is a very big pleasure for me. I am willing to answer all of the questions people have about these topics.

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