Honda Tighten Fuel Cap: Causes & How To Fix

The “Tighten fuel cap” message shows up whenever you are required to check the fuel cap to ensure that it is secure. The message indicated that the ECM had discovered a leak in pressure in the vehicle’s fuel tank. Besides this, a very common cause for this issue is a missing or damaged cap or one that is not tightened enough.

There are various Honda models common with this issue: Civic, Odyssey, Insight, Ridgeline, CRV, HRV, and Acura. Having this issue is no cause for alarm. With this in mind, you can simply fix the issue at your convenience.

To explain further, this guide will look into the “Tighten fuel cap”, the causes for this message, and how to fix it.

The “Tighten Fuel Cap” Message Displays On iMID

There are various reasons why your Honda vehicle might display this message. Some of these are introduced below:

Missing Fuel Cap: This is the most common cause of this message. Frequently, it results from a fill-up.

Loose Fuel Cap: There must be a satisfying click when tightening the fuel cap.

Damaged Fuel Cap: You will find a seal in the gas cap that is safely placed close to the fuel inlet. A bad gasket will lead to the escape of the fuel vapor. This will result in the “Tighten Fuel Cap” warning message.

Other causes for the message include the following:

Possible Solutions To This Issues

There are different ways to tackle this issue:

Follow Honda’s manual

If a missing or loose fuel cap is the cause of the message, follow this process:

  • Turn off the engine
  • Confirm if the fuel tap is fully installed. If not, loosen the cap, and retighten it until you hear at least one click.
  • The “Tighten fuel cap” message should go off once you turn off and on the ignition switch and drive for some days. The distance it takes for the light to go away depends on the driving conditions. Usually, this may take up to 10 miles or 100 miles.

However, if a missing or loose fuel cap is not the cause of the message, the message will go off, and the Malfunction Indicator Light (MIL) will turn on. Once you experience this, contact your dealer immediately.

Remove the cap and access the seal area on the cap and the filler-neck

The message may come from gas cap issues. Take the gas cap off and check if it is torn. In that case, you can contact your dealer for a warranty. Besides, if it seems clean, it is possible you have a bad cap. When this happens, you can have the dealer replace it or simply visit Amazon to purchase a new one for about $16.

Get rid of the message without driving

If you wish to clear the message without the need to drive, try turning on the car and turning it off for about 4 to 5 times. 

Another measure is to turn off the car, disconnect the battery by detaching the negative terminal. Then, wait for about 10 seconds before you reconnect it. The message should clear once you start the car. 

Furthermore, pressing the “Reset” button is also an effective way to get rid of the message temporarily.

An Aftermarket intake or Throttle Body Spacer could be the cause of the error message

If there is an aftermarket intake or Throttle Body Spacer (TBS) on an R18 engine, this could cause the error message. In this case, remove it and see if this clears the message. If not, you can adopt a simple fix that involves placing the rubber ring on the opposite side of the spacer.

Get in touch with an authorized dealership

If the message keeps coming up, it could result from a bad evaporator canister. Simply contact a dealership to help you replace it.

Why Does The Message Go Back After A Short Time?

It must be stressed that the message will not go away immediately once the cap has been tightened. Even though it is possible to press the “Reset” button to cycle the message, the DTC setting the message still remains there. This implies that the message does not really go away.

The “Reset” button can recycle the message back, and it can show up again if the engine is restarted. You will keep getting the message unless the EVAP monitor checks thoroughly and sees no system leak. 

Oftentimes, you might need to wait for a while, based on how frequently the vehicle is driven. If the warning remains, you can consider a bad Purge Solenoid Valve.

What does the “Check emission system” mean?

Some Honda Civic owners have complained that the “Tighten fuel cap” and “Check emission system” messages often appear at the same time.

The “Check emission system” message means that there is an issue with the vehicle’s emission system. When this warning light comes on, it implies that the vehicle’s onboard diagnostic system has detected a malfunction in the Emission Control System.

What this system does is that it limits the number of harmful gasses that go into the atmosphere by releasing them into a closed system. There are some common issues that can turn the “Check emission system” message on. Some of these include:

  • Damaged fuel lines
  • Loose gas cap
  • Faulty spark plugs

How to fix

To get rid of the “Check emission system” message, you can consider the following:

  • Contact your dealer to help replace the whole gas tank, which should cost about $875.
  • You can also turn off the engine by using a wrench to detach the positive power cable of the battery. Leave for a short while before turning the ignition on and off. Then, you can reattach the power cable. Once you turn the ignition back on, the light should go away.
  • Another solution involves turning the car on and off three times, without interruption. This should make the light go off. 

Yet, the best way to reset the “Check emission system” light is to diagnose and solve the problem.

Getting The “Tighten Fuel Cap” Message In The Cold                  

Even when the fuel cap is tight enough, you might get the “tighten fuel cap” message in the cold. This might be a result of a clogged or damaged gas gasket.

How to fix

To fix this issue, all you need to do is wipe the gas cap gasket and use a little quantity of silicone lube or vaseline as you get the gasket a little bit wet. Then, you can put it back on.  Silicone lube is used since it goes well with rubber without breaking it. 

If that does not work, you can simply replace the gas cap.

Getting “Tighten Fuel Cap” Message and Gas Fumes In The Car

Whenever there is a loose gas cap, it can permit contaminants into the fuel tank of the vehicle through cold running. As this happens, the moisture and dirt can emanate from the evaporation of the gasoline, which may cause the engine to misfire.

How to fix

To fix this issue, clean the tank fill area while gently cleaning the cap seal. Then, check if the internal valve is good.


1. Can a loose gas cap cause the “Check engine light” to come on?

Yes. A loose gas cap can cause the “Check engine light” message to come on. Fixing this issue is straightforward:

  • If the gas cap is damaged, simply replace it.
  • If you have a loose gas cap, tighten it about 3-4 clicks.
  • Drive for several minutes and the malfunction indicator light should go off. 

2. What happens if you don’t tighten the gas cap?

Several issues may result from failing to tighten the gas cap. These include bad engine performance and fuel efficiency. Besides this, an untightened gas cap might pose a significant threat to the environment.

A loose gas cap can also fritter away the vapor recovery system of your vehicle. In addition to this, the Evaporative Emissions Control System is an essential component, and having a loose gas cap can damage it.

3. Can you drive with a loose fuel cap?

It is not safe to drive with a loose fuel cap for many reasons. As technology advances, car manufacturers have invested so much effort in providing – and enhancing – various safety features that can assure safe driving.

The fuel system is one of these features. Some valves ensure that gas does not flow back out from the tank. Driving with a loose or damaged fuel cap can decrease engine efficiency in the long term. Dirt and other impurities could find their way into the fuel system, resulting in engine damage.

In addition, the absence of a fuel cap can ensure that harmful fumes can escape into the environment.

4. How can you tighten a gas cap?

Tightening a gas cap is quite easy. Just follow my step-by-step guide below:

  • If your car has a locking fuel door, pull the fuel door release lever after turning your car’s engine off.
  • Open the fuel door to release the gas cap.
  • Pump the gas, but do not top off the tank. Immediately the shut-off kicks in, stop pumping.
  • Push the gas cap down the fuel port.
  • Turn it clockwise until there are 3-4 clicks. This tightens the gas cap properly.

Final words

The fuel cap is a crucial component of a vehicle, promoting safe driving. Seeing a “Tighten fuel cap” message is no cause for serious concern. You have no reason to panic. It is a common issue among various Honda models, especially Honda Civic.

The message is most likely to result from a missing or loose fuel cap, among other causes. As mentioned above, there are various quick fixes you should acquaint yourself with.  Finally, it should be stressed that readers can follow the aforementioned tips to fix the message.

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