Honda “Check Fuel Cap” Warning Causes

A very common message to see when driving a Honda made vehicle is “Check Fuel Cap”.  This message obviously wants you to check the fuel cap to make sure that it is on and secured.  Why though?  



The check fuel cap indicator means that the EVAP system has detected a leak.  Far and away the most common reason for this problem is that the fuel cap itself is missing, not tightened enough, or damaged in some way.

If this has happened to your Honda, make sure you put the cap back on someplace safe.  There is no immediate danger, and therefore no reason to pull off the road someplace dangerous to do this.


“Check Fuel Cap” Symptoms

Your Honda will still run and drive just fine.  The only thing you may notice is the slight smell of fuel (particularly if your tank is full).


“Check Fuel Cap” Causes

Most of the causes related to the check fuel cap message are going to actually be issues with the fuel cap itself.

Check Gas Cap Honda
A bad gas cap is one of the top reasons people smell gas coming from their vehicle

Gas Cap Issues

  • Missing Fuel Cap– This often happens after a fill up.  With no fuel cap on the message will populate right away.  Replacing the fuel cap will clear the message.
  • Loose Fuel Cap– When tightening a fuel cap, it needs to be tightened until there is a satisfying click.  If that click is no longer being felt, it is time to replace it.
  • Bad Fuel Cap– There is a rubber seal in the gas cap that snugs against the fuel inlet.  If this gasket has gone bad the fuel vapor will be able to escape through the cracks and the “Check Fuel Cap” light/warning message will appear.



Your fuel tank is part of your Honda’s larger Evaporative Emissions Control (EVAP) System.  There is a certain amount of pressure in the tank.  This pressure is secured by the fuel cap.

Your Honda’s computer will throw the “Check Fuel Cap” warning when it detects that the pressure has changed enough that it’s likely that there is a gas cap leak.  Otherwise, it would have thrown an EVAP related trouble code (most likely P0457).


“Check Fuel Cap” Fix

Check to make sure that the fuel cap is tightened.  If it was loose, you’ll need to snug it.  It may not immediately turn off the fuel cap warning.  Drive for a couple days.  

If it still does not clear you should inspect the gas cap for any damage.  Take a good look at the O-ring.  If it is missing or damaged, replace the cap.

If the gas cap is OK and the message is not going away there is likely a leak in the EVAP system.


How to Check the Fuel Cap

  • Open the fuel door.
  • Twist the fuel cap to the left until it disengages from the fuel fill nozzle.
  • Put the cap back on.  Make sure the threads are lined up correctly and twist to the right until there is a click.


Is it Safe to Drive Without a Gas Cap?

It is safe to drive with the gas cap light on.  In fact, it’s a lot safer than pulling over to the side of the road.  The built in flapper valve will keep the fuel in the tank even if the cap is entirely missing.


Wrapping Up

Gas caps can and do go bad.  They are not made to last the entire life of the vehicle (although some often do).

The check fuel cap warning is almost always caused by a bad or loose gas cap.  It sometimes can indicate an EVAP leak.  If there is anything that you could add to help the next person reading this article, please leave a comment below.  Good luck!