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Check Engine Light Comes On After Getting Gas – What’s Wrong?

The check engine light is a warning signal on the dashboard of cars used to indicate a malfunction. As a car owner, you may wonder what is wrong when your check engine light comes on after getting gas. Fortunately, we have done the research for you, and here is what we have found out.

There are different reasons why the check engine light comes on after getting gas. Here are some of them:

  • Loose gas cap
  • Damaged gasket
  • Faulty vacuum hose

These problems should be tackled as soon as possible, so it doesn't get worse. Keep reading to get detailed information about issues that may cause your check engine light to come on after getting gas and how to fix them.

Engine check light on car dashboard - Check Engine Light Comes On After Getting Gas - What's Wrong

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What Could Be Wrong If My Check Engine Light Comes On After Getting Gas?

Whenever you notice that your check engine light is on after a refill, it could be due to various issues, some of which can easily be avoided or corrected immediately. Here are the possible causes of the problem:

Loose Gas Cap

Leaving your ignition on when your gas cap is off can result in your check engine light coming on as your car senses the loss of pressure from your gas tank.

As small and insignificant as a gas cap might seem, it is an essential part of a vehicle. Its functions include ensuring that there is no loss of fuel from the car, preventing the entrance of debris that could mix with the fuel, and maintaining a high fuel efficiency by ensuring no gas vapor loss.

The check engine light may come on when you fail to tighten your gas cap properly after a refill or your gas cap doesn't click when closing. If you notice this problem after getting gas, quickly check and tighten the gas cap. You can replace the cap if it refuses to click or pops open after clicking.

Damaged Gasket 

The gasket on the gas cap serves as a seal, preventing leakage of gas vapor or fuel. It also stops from getting into the gas tank.

When the gasket on your gas cap is bad, you can no longer rely on the sealing function of your gas cap as leakages and entry of dirt won't be stopped. This may cause your check engine light to come on. To solve this problem, you should replace your gas cap.

Faulty Vacuum Hose

A vacuum hose is a tube that transmits a vacuum from the manifold to wherever it is needed. Vacuum tubes are used in various compartments of cars. There are different types of vacuum tubes varying from the materials they are made of to the size of their internal diameter, which is usually smaller than the outer diameter.

Because vacuum hoses are mainly made from rubber, they tend to wear off easily, causing a vacuum leak. This implies that even if the injectors are working properly by sending fuel into the cylinders, unburned fuel is entering the exhaust system. This can cause damage to your catalytic converter because the fuel is not getting combusted.

A damaged vacuum hose can easily be replaced, as long as you know the internal diameter size. You can also err on the side of caution by going to a professional to help with the replacement.

Engine malfunction warning light control in car dashboard.

How Many Times Should I Click A Gas Cap?

A gas cap is built so that it clicks once it is well-tightened. Many manufacturers reveal it is best to ensure that it clicks at least three times, but the number of times it clicks does not make much difference. The goal is to click it at least once.

It is possible to over-tighten your gas cap, especially when you don't stop at just one click. It is advisable to avoid over-tightening your gas cap as it can make the gasket of your gas cap go bad.

How Do I Know When To Change My Gas Gap?

Testing a gas cap helps you know when it is due for a change. Sometimes, a gas cap may be faulty even when it is not loose. If you are taking your car for maintenance often, your mechanic can also inform you if your cap has a problem and if it needs to be replaced. Here are signs that you need to change your gas cap:

  • The smell of fuel in your car
  • Poor fuel economy
  • A noticeable coloration around the edge of your gas tank
  • Damaged or loose gas cap

Can I Drive When My Check Engine Light Is Active?

Check engine light illuminated on dashboard.

When the check engine light is active, there could be a malfunction that may or may not be an immediate problem for your car.

You can still drive a car with its check engine light on. However, refusing to fix the detected problem after a long time could result in more damages that may cost a lot to repair. Solving all issues detected as soon as possible is recommended to avoid further damage.

Can I Use Scanner To Reset My Check Engine Light?

After fixing the problem with your car, your check engine light may not go off. When this happens, the way to turn it off is by resetting your check engine light. Luckily, you can easily do this on your own without the help of a professional.

You can use a scanner to reset a check engine light if you have a problem driving your car for a long time with the check engine light on. An OBD2 scanner has a double function of diagnosis and resetting the check engine light.

The car's internal computer undergoes what is called a "cycle." A cycle is a phase when you turn your car on and turn it off again. The car's internal computer automatically resets after a period where it has checked all of its sensors. However, this can be after a varying period of 10 to 20 cycles.

The computer monitors all sensors when driving, and results are usually registered. The readiness monitor remains as far as the vehicle is driven for a long time before letting the computer recheck the different sensors and systems. The amount of time often varies and may depend on the vehicle. In some cases, every computer monitor may take up to 100 miles to reset. 

How Many Miles Does It Take To Clear A Check Engine Light?

Engine malfunction warning light control in car dashboard.

Some vehicles' check engine light stays on after a reset. In this instance, a way to clear the check engine light is to drive around for about 50 to 100 miles.

The catalyst and EVAP monitor work slowly, so your vehicle cannot pass an emission test if your light has been cleared or if you reset the check engine screen before your test. In a disconnected state, your car tends to fail automatically.

Will Check Engine Light Come Back On After Cleared?

The warning light may disappear if the code is cleared. However, the codes of the engine may appear once every week. Immediately most car owners clear ECU codes or stop using their vehicle for about a week, and the light comes up again. This is because the ECU does a series of tests after it starts to function. 

The emission will pass only when your vehicle is not powered on during arrival at the test location. When the repair is ongoing, the technician usually removes the trouble code. This is to avoid going against safety laws. If there are any trouble codes, even minor, your vehicle may fail the emission test.

Car refueling on the petrol station. male employees controlled the fuel pump with Fuel nozzles adding gasoline fuel in car at a pump gas station.

To Wrap Up

You can easily resolve most problems related to the check engine light coming on after getting gas. It is advisable to tackle the problem as soon as possible, even when your vehicle does not indicate an immediate deterioration due to the problem. When your check engine light comes on, you should check for a loose gas cap, damaged gasket, and faulty vacuum hose.

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