I am currently out of town (of course) and getting a message that says "check fuel filler cap." Well, I've checked and it's fine. Another strange behavior is that my fuel gauge will show the tank being half filled when I know I just put around $40 of fuel in the car and it should be showing full. Don't know if that's related to the "check cap" error.

The car will run fine until it uses a half tank of fuel, then the gauge will start working properly and shows how much fuel is left in the tank for the remaining half tank.

Does anyone have any clues as to what would trigger the "check fuel filler cap" error message. I'm about to head to the gas station for fill-up and report back of any strange behavior, such as difficulty filling the tank.

Any thoughts would be appreciated.

 

Are you leaving the car running when you fill the tank?

 

Think things through: the car is detecting SOMETHING. It can't actually go round and check the cap like you can. So, IF you're sure it's fitted properly AND seals properly then the car is seeing something else and doing its best to tell you what would probably be the cause. You have other clues such as the odd fuel gauge. Whether you have a single fault or multiple.... well, the single is the more likely. Beats me what it is, though! Try one of the sources of car data when you're home, including maybe a dealer or indy.

It will probably be worth having a good look round the filler and any tubing and wiring you can locate. Loose piping, chafed wires etc would be prime suspects.

The car's probably trying the EVAP system and finding it has a "leak" - a big one - and usually that's the filler cap. So OBD may help especially mode 6 for the evap.

 

Keep in mind that just because your fuel filler cap closes and clicks normally, that does not necessarily mean that it is sealing properly. On many of today's cars, these relatively cheaply-made caps are the first component to fail in the fuel system. Over the years on several different vehicle forums, I've read countless posts where replacing an original fuel filler cap solved the problem of various codes being thrown....

 

Agreed.

 

Thanks for the feedback guys. It did cross my mind to order a replacement for the filler cap, although it appears to seal properly.

And for the question of is the engine off when filling up, yes it is.

Maybe the Evaporative Canister is suspect.

 

If the 2 faults occurred together there's probably a common cause.

The canister can't really be it but the valves etc might be. I don't see how they'd affect the fuel gauge, so I doubt it. A dealer tool can test the evap system as well as read any non-generic OBD codes.

 

I would start by cleaning the sealing surfaces of your fuel filler cap as well as the area on the fuel filler tube where the cap seats against it in the closed position. I would use some silicone spray on a clean rag with plenty of elbow grease.

If that doesn't correct the issue, my next step would be to obtain a new fuel filler cap.