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Tighten fuel cap message

Thetryal

Full Member
Joined
Jun 6, 2021
Messages
9
2005 Avy 2wd 1500, 175k miles

I keep getting the message to "tighten the fuel cap". The check engine light does not come on but when I scan for codes, it shows p0455.

I was having a hard time putting fuel in the gas tank. I have replaced the fuel cap, vapor canister, the solenoid, and the purge valve as well as sucked out the carbon pellets that clogged up the lines. I can fill up the tank with fuel but every morning on my way to work, the truck dings and gives me the "tighten fuel cap" message.

Any thoughts on what to replace next or how to get this to go away?

Thanks in advance
 
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Well the cheapest things would be to literally check the cap itself. Make sure there's nothing between it and the fuel filler neck. Make sure the gasket is present in the cap and it's clean.

Caps themselves are super cheap online as a hail marry.

Beyond that, you'd have to get the evap system smoke tested. That's the simplest way to see if it's leaking from a connector or if there's a small hole in something. You've replaced a good amount of it. The cap, lines, and sending unit are all that's really left, assuming all of the connections were done properly.

It also can take some time to clear the code. It took my tahoe about 10 miles to clear it after i realized the tether had come off the neck and got between the neck and the cap. A 2005 has a better tether though.

The cap error should signify a large evap leak though. Large enough that it assumes the cap isn't on right. I'd give all the connections a good check.
 
Appreciate the reply. I have cleared the code but like clockwork, every morning, ding, check your gas cap. I'll check the connections and get the smoke test.

Thanks agaon6
 
buy new cap.
 
The cap I currently have is the 2nd cap I have tried. I still get the message.
 
If you tried everything else,

I would tighten the fuel cap...

(sorry couldn't resist - and as a disclaimer, I am not tempting fate, I feel for you as gremlins are a PITA)

I agree with Raekal in that maybe too much air is getting in the system. Maybe you should double check all the lines and clamps to be sure all is sealed well.
 
The cap I currently have is the 2nd cap I have tried. I still get the message.
OEM or aftermarket fuel cap?

You've nearly replaced the whole EVAP system, save for a couple lines to/from tank, canister and purge valve. Time to smoke test it, like you already said.
 
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