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Can Bad Gas & Gas Cap Cause Check Engine Light? (Answered)

Check engine light is a revolutionary indicator for a modern car. It will save you from upcoming accidents and will let you know about internal issues. Also, you can quickly know if there is anything wrong with the engine or other parts of the vehicle.

At the same time, the check engine light will give you an indication of gasoline and gas caps. You can consider this engine light as the malfunction indicator from this perspective.

Whenever and wherever your car gets any damage or wrong, it will indicate the light. In that way, you can take action accordingly.

However, bad gas and gas caps are two multifunctional parts of a vehicle. Most of the time, we ignore them for a long time. As a result, we face issues and damage to our engine too. Here, the check engine light will show a great relief.

Can bad gas cause check engine light?

Bad gas can cause check engine lights in maximum situations. Your check engine light will not indicate anything for the bad gas in normal conditions. But if the engine fails to get enough gas and struggles to start, it will show you the engine light. However, you can sort out the problems.

When you don’t change the bad gas for a long time, you will get a bad gas check engine light code. But for the first time, you can sort out the issues by replacing the engine oil and putting in a quality oil.

After running the car, bad gas mileage, no check engine light. But if you truly have bad gas, check light flashing will be an excellent meet for you.

However, bad gas is not good in any way. It will damage the car engine and tank as well. That’s why you should always check the engine light.

What are the symptoms of bad gas in your car causing check engine light?

The symptoms of bad gas in your car causing check engine lights are given below:

Struggle to start:

When you struggle to start the engine, you might have bad gas. This is the first symptom you will get for bad gas or fuel.

Car stalls hardly move:

If your car stalls and you hardly move it for the first time, you should check the gas quality or level. It is the second symptom of bad gas and will get engine light.

Get engine light on:

If you have an engine light, it will cause bad gas when the engine does not get enough fuel. Bad gas will reduce the gas flow to the engine; therefore, you will get an engine light.

Damage fuel tank:

Bad gas will give you light if your tank goes wrong. Sometimes, the bad gas will ruin the internal health of a fuel tank. Therefore, it will be clogged; as a result, you will see an engine light.

How to fix bad gas in a car to check engine light?

To solve the engine light for bad gas, you need to fix it. In that case, you can follow some steps.

Check fuel line:

First, check the fuel line that supplies oil to the engine and generates power. If you have bad gas, you will get clogged over there. So, you should clean it first.

Fix bad gas:

To fix the bad gas, you can pour pure fuel on the tank and fill up the entire tank. That will be the easiest way to sort out the issues. In that way, you may find the engine light for a couple of days, but it will be solved automatically.

Chang tank fuel:

If you use the bad gas for a long time, you might already damage the engine and cannot sort out the issues by following previous steps. In this regard, you have to change the tank fuel and clean it properly.

Clean tank:

You can depart the tank from the car, then clean it and fill it with high-quality fuel. Then you can start driving the car. That’s the ultimate solution to the bad gas.

How to test for bad gas in a car?

To test the bad gas in a car, you can simply look at the engine light. When your car gets too much bad gas, it will show you an engine light now and then. It will be the best test.

At the same time, you can physically test the bad gas in a car. For that, you need to open the fuel tank, then check the smell. IF you find any sour taste or smell, it is bad gas.

Also, you can check the color. If you regularly drive the car, you will know that fuel has its fresh color. On the other hand, when it goes bad it will have a dark color. Therefore, you need to change the fuel.

These are the two best ways to test the bad gas in a car. On the other hand, you can also check the symptoms of bad gas.

Can bad gas cap cause check engine light?

The bad gas cap can also check engine light. It’s another major concern for the engine. When you have a bad gas cap, that means your engine also gets some additional ingredients, including dust and bacteria that grow in oil. Therefore, it will go wrong and will react.

Moreover, bad gas caps also lead the tank to leak. If it happens, it will lead to a misfire in harsh conditions.

On the other hand, a bad gasoline tank cap may damage the entire vehicle’s health. It will also increase your cost since the gasoline or fuel will seep through the leaks.

Why does the gas cap make check engine light come on?

For some reason, the gas cap male check engine light comes on. They are:

Ruin tank health:

The gas cap sometimes goes bad. In that time, it will make the gas bad and ruin the tank’s health. In that case, your engine doesn’t get quality oil to run. Therefore, it shows the check engine light.

Clog fuel line:

Another reason could be the clog on the fuel line. Therefore, the engine will struggle to start. As a result, you will get an engine light coming on.


Moreover, the gas cap plays a crucial role to indicate the malfunction in the tank. If it gets leakages and fuel goes out, it will show you the engine light.

Will the check engine light go off after tightening the gas cap? Will the check engine light go off after replacing the gas cap?

If your gas cap is loose, you will notice the check engine light. It will go off after tightening the gas cap for sure. If you still find the engine light coming on, you should run the car for minutes. It will go off if you tighten the gas cap.

On the other hand, if your gas cap is too bad, you should change it unless you will get the check engine light. After replacing the gas cap, you need to tighten it perfectly. Then the light will go off.

How long does it take for the engine light to go off after tightening the gas cap?

20 minutes is the highest your engine will take to turn off the light after tightening the gas cap. But it will turn off the light within a couple of minutes if you run the car without any brakes.

On the other hand, your engine lights will keep coming if you forget to tighten the cap perfectly. You need to cross-check the cap and be sure to firmly close it.

How do you fix a check engine light on a gas cap?

To fix a check engine light on a gas cap, you can follow our tips and steps. They will help you to stop the light from coming on.

Check gas cap:

You should check the gas cap. You can simply open the cover and go to the fuel tank. Look carefully; if you find any leakage or a loose cap, you should close the cap.

Tighten it:

It’s time to tighten the cap firmly so it does not come out, and you will also stop the engine light soon. After tightening the cap, you should re-check the cap if it has any leakage.

Look for leaks:

If you find the cap has some leaks, you should replace it with a new one. It will be your best solution regarding gas cap issues. Here, you can buy the premium quality gas cap and ensure the safety of your fuel tank.

Final Thoughts

Both the bad gas and gas cap can turn on the check engine lights. You will find them coming now and then. For some reason, the light will go off after running the car for a couple of minutes. That’s not the solution. You need to change the bad gas and gas cap if needed. That will be the solution.