Today: The Case of the Missing Fuel Cap Flap

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Dear Tom and Ray:

I drive a 2005 Honda Accord. Recently, I started getting a "check fuel cap" message on my dash. When I checked it, it was properly tightened, but the message kept appearing. I went so far as to remove the cap completely to check and make sure everything looked normal, at which time I noticed that the metal flap that normally covers the opening of the tank was missing. How this happened is beyond me. How serious a problem is this? Am I going to explode driving down the highway, get 2 mpg, contribute even more to global warming? Is this going to cost my life savings to fix?

-- Kate

TOM: The answers to your questions are no, no, maybe and no.

RAY: I've never seen the little flap fall off, but I suppose it's possible. It's just a flimsy, hinged piece of sheet metal to prevent backsplash when you remove the gas cap to add fuel. And I had no idea the flap had any connection to the emissions system or the "check engine" light.

TOM: I don't think it DOES have any connection. Nor would the flap do any harm if it happened to fall into the gas tank. It would just sit at the bottom of the tank forever. But we DO know that if your gas cap is faulty or not tightened completely, that WILL make the "check engine" light come on (or the "check gas cap" message in your car, Kate).

RAY: That's because a poorly fitting or loose gas cap allows fuel vapors to escape into the atmosphere, which creates smog, which turns Los Angeles into Beijing.

TOM: And despite the mystery of the missing flap, you may just have a bad fuel cap. So here's what I'd do. Go to the Honda dealer and buy a brand-new gas cap for $25. Install it and see if the light goes off after a few days. If it does, you just needed a gas cap, and the whole flap "flap" was just a distraction.

RAY: If the new cap doesn't solve the problem, then you'll need to have a mechanic look at it for you. Perhaps the top of the fuel filler neck got damaged somehow, and that's preventing the cap from making a proper seal. Or maybe there's something else preventing the fuel system from maintaining proper pressure.

TOM: But rather than start by paying $150 for the dealer to scan your car and do a bunch of tests, start with a gas cap. It's cheap. It's easy to install yourself. And it may be all you need. Good luck, Kate.

Comments

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Michael Little

Sat, 2011-12-24 16:40

Ahhh the fuel cap problem- Google Honda fuel cap problem and join the multitudes that enjoy this Honda Problem do not worry -most other brands have the same. My 2010 Honda CRV Check Fuel Cap Message went on 4 months- Sunyside Honda Cleveland Ohio and American Honda Torrence CA were mystified- no idea - ran tests and keep telling me for 4 monthsthat the fuel cap was loose. They changed the fuel cap first thing-problem still there cause it was not the fuel cap. I read on the Internet another fellow had my same problem and experience for 18 months. Our mutual problem was caused by a faulty Purge Pressure Soleniod Valve. Honda EVAP test cannot detect this problem when this part goes bad. However if the Engine Check light goes on the cars computer will tell the service dept that it is this PPS valve. My engine check light went on at 98 days for less than a day but was enough to give a repair code. Now Honda will not change this PPS valve unless their test show that this is the problem. The problem is that the Honda trouble shooting test that will not detect this valve problem and their valve design flaw that permits this part to go bad. This faulty PPS valve also affected my mileage range indicator and my average miles computation. Hope this helps. Another option seriously is to sell the car- after all if the manufacturer and the dealer lack the ability to repair their product- happens when something really bad comes up?

TOM B1

Sun, 2011-12-25 18:40

On some models of Honda and Isuzu vehicles the fault light or fuel cap light may come on, I have found out that it is not a sensor or cap, it a rusted through fuel vapor lines or main fill tube, cheap metal tubing that it painted black holds in moisture and rusts pin holes in the tubing. Most of the time you wont have a visable gas leak but may smell fumes.

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Michael Little

TOM B1

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