This problem is usually a gas cap that is not tightened all the way, or has a bad seal, but can be other issues.
Once the problem is fixed, the car will need to be driven for a while , called a Drive Cycle, before the message disappears.
What Causes a Check Fuel Cap Message on a Honda Accord?
This helps to reduce smog-related emissions.
The system works by setting a vacuum in the gas tank, which the onboard computer (ECM) monitors through a sensor.
When a vacuum is lost, the sensor will detect this as an evap leak, and the ECM will give the message Check Fuel Cap.
After the evap leak is sealed, the car will need to be driven through a drive cycle for the error to clear.
An OBDII scan tool can read codes which often include P0440, P0443, P0442, and P0449.
4 Causes and Fixes for Check Fuel Cap Message Honda Accord
- Be Sure the Gas Cap is Screwed all the Way In
- Replace the Gas Cap
- Evap Leak
- Bad Purge Valve
A cap that is not all the way in will lose the seal, causing issues.
When turning it in, it should click a few times, which lets you know it is in all the way.
Also, check for any debris that may be causing the cap to not make a good seal.
There is a rubber seal inside that rings the cap and makes a seal when screwed into place.
Examine the rubber seal to see if it is broken or old.
Often the cap can be replaced to rule it out a possible problem.
When a new cap is ordered, be sure to get the right one for your make and model.
Gas caps can be bought at auto parts stores or ode online on Amazon or eBay.
Be wary of non-genuine Honda gas caps, which sometimes do not work.
The non-genuine gas caps sometimes work and cost less but can cause issues since they may not seat properly.
Genuine Honda caps are best to buy to rule out the cap as a possible problem.
Example Honda Gas Cap on Amazon
Honda Genuine 17670-TR0-A11 Fuel Filler Cap Assembly
If there is a leak in the Evap system, it can give the “Check Fuel Cap” error message.
Evap leaks can be had to spot unless the hose has been torn off or have another visible issue, such as a cracked hose.
Mechanics often use a smoke machine to feed smoke into the system, which will come out at any leak location.
There are low cost smoke machines as well as YouTube videos for DIY smoke machines that can help find an Evap leak.
When a car is off, the purge valve closes, stopping any vapors from escaping.
When a vehicle is running, the purge valve opens and allows vapors to go to the charcoal canister and burn in the engine.
Common problems with the valve include sticking and not closing.
Can I Drive with a Check Fuel Cap Message Honda Accord?
Usually, yes, you will be able to drive the car as most Evap leaks only affect the vehicle’s emissions.
In some rare cases, it may cause the vehicle to run poorly, which will make it undrivable.
If the car runs badly, there are likely more problems than a normal Evap Leak and will need to be looked at by a mechanic.