Gas cap won't stay tight....

[Erkelbot]

Just buy a new one from Toyota. It's like $24 -- I just had to do this myself. OEM is pretty much always best for applications like this.

 

[BlackWorksInc]

just go to the dealership the aftermarket ones are junk I cant tell you how many times I have to sell factory ones when customers tell me the aftermarket one didnt work

That's about right... a lot of the aftermarket ones don't seem to last or fit well.

I replaced my gas cap a year or so ago because the rubber just became hard and flattened out and would loosen up over time. It's a rubber part on a 10yr old vehicle, I'm not surprised it failed and a new factory cap is cheap enough.
[MENTION=113419]dr_UMMER[/MENTION]

There's nothing wrong with replacing a failed part with a new one. You're making an assumption that the original part wasn't good or that it was defective.

 

[joemot]

So got the CEL with code p0456 for the fuel system, gas cap not tight. Went to check it and sure enough it won't stay tight. I went out and bought a new one with the same issue. They both click but never tighten down. My only other guess is that for some reason the metal part of the filler neck is worn down thus not allowing it to tighten. Anyone ever had this happen before and know a fix? Thanks

Replace the o-ring.

https://www.amazon.com/gp/product/B0085L3FEO/ref=od_aui_detailpages00?ie=UTF8&psc=1

 

[olyeller]

So my cap is very loose, basically the tabs just stay in that little notch but nothing holds it in. But I’m not getting a check engine light. Should I normally have one on if one forgets to replace the gas cap, for example?

 

[Charlie Hustle]

I found a different solution for the exact same problem, many others seem to have. I have 04 SR5 and my gas cap would not stay on tight, since I had no idea how old the gas cap was, I purchased a brand new OEM Toyota one on Amazon. CEL and TRAC Control lights turned off. Seemed like the problem was fixed. Unfortunately, this only lasted a couple of months, and the new cap became loos and the CEL came back on. I finally discovered what was not allowing the brand new cap to stay on, and have a tight fit...

It was the damn teether cord that connects to the gas door. It will not allow you to turn the cap enough for it to click and lock into place. I cut the teether off, and the very first time I attempted to turn the cap, it clicked once and is very tight now. I was never able to do that with cord connected. I hope this helps someone who was dealing with the same annoying issue, and thought it was either a bad cap, or a O ring.

 

[drallan]

My wifes 04 v8 was throwing codes and I got a call one day that all sorts of lights came on! I have a bluetooth OBDII always connected and torque on her phone. Had her look up the code and verify it was just the "loose gas cap", not having a new cap on us I had her just rub some neosporin (vaseline) around the gasket and rim of filler neck. CEL went away (might have had to clear it) and hasn't returned in a few months. I did order a new cap, but haven't replaced yet. Keep it in the car, probably will next time if/when the CEL reapears.

Maybe just try a light smear of vaseline or other lubricant/sealant and see if that helps. FWIW her cap feels like it doesn't tighten at all. Tightening it clicks a few times and feels good, but a butterfly could loosen it.

 

[IowaHawkeye53]

Just bought my 2008 at a Lexus dealership two weeks ago. I realize they could not have known this but the fuel sending unit was bad and sending false readings to the fuel gauge. Wife ran out of gas on the interstate. SMH. This was in the first 5 days of ownership. Now a week later the CEL/VSC lights come on. Got a lot of info from these threads to check on so Hopefully it is the cap or something easy. Just spent an extra $800 replacing the sending unit and since we had the fuel tank out we replaced the fuel pump. Not getting a fuzzy from my first 4runner but I hoping for better times ahead.

 

[brajaharidas]

I had a similar problem in that the gas tank cap was not staying tight. Like you said, i would click, but would loosen immediately. But buying a new original gas tank cap from the Toyota dealer fixed the problem.

 

[THatSOT]

My 2009 V8 just threw check engine codes P0441 and P0455. Been searching for possible causes and solutions. For my particular case, long story short is it was the bad gas cap (clicking but not actually staying sealed, at all). Bought the replacement from Toyota dealer today ($31), installed it, cleared the codes with my bluetooth little reader/scanner. So far so good.

I didn't think it was the gas cap at first. Besides, I swear I just replaced it with one I bought from Toyota dealer probably about a year or so ago. Probably from receiving one of the EVAP check engine codes. What threw me off, and the reason I'm writing this post (lurking around this board more than 10 years as guest, just joined and this is my very first post) was I focused on how the gas cap was tighten/closed. I thought as long as it made the clicking sound, everything was good (tight and sealed). As I found out today, that is not necessarily true. Gas caps made years ago (as in 20+ years) used to require some unscrewing efforts. Gas caps nowadays, when you unsrew them, they would unscrew so effortless and quickly, I didn't realize my old gas cap was no longer had any seal, no resistance, at all. And now as I think about it, it could have been loose like this for quite a while.

Not sure if this has anything to do with another "pre-existing condition", namely my fuel data sending unit has been bad. The fuel gauge routinely shows much less gas than I know my tank actually has. I fill her up, it shows I have almost 3/4 tank full. But having this fixed is too costly so I have been trying to live with it.

Thanks for bearing with my first and lenghthy post.

 

[808g19]

1/2/2020 I took the rubber o-ring off and flipped it over then reinstalled, seems to have a bit tension now. Erased the CEL. I'll see how that works out.

 

[808g19]

Update on o-ring flip over, it works! So far no lights came back on.

Sent from my moto g(7) power using Tapatalk

 

[Syr4RinNC]

Update on o-ring flip over, it works! So far no lights came back on.

Sent from my moto g(7) power using Tapatalk

+1 for flipping the rubber gasket seal over - it definitely screws on and unscrews better. Its simple and elegant

We'll see how it goes with the CEL and how long it lasts for, but helps with the loose unscrewing tensions for now.

I also lathered it with vaseline

 

[hliang]

I have the same problem

The gas cap clicks but doesnot tighten. I went to Autozone and bought a new one, and still the same, it clicks but it is not tightened. I feel no resistance at all when unscrewing the cap. My question is: is this normal? Should it have some resistance when I unscrew it?

 

[AuSeeker]

The gas cap clicks but doesnot tighten. I went to Autozone and bought a new one, and still the same, it clicks but it is not tightened. I feel no resistance at all when unscrewing the cap. My question is: is this normal? Should it have some resistance when I unscrew it?

Mine is similar feeling and I have no issues, if the cap wasn't sealing completely you would get lights coming on in the instrument panel because the fuel evaporative system would trigger them if the system isn't sealed correctly.

 

[hliang]

Mine is similar feeling and I have no issues, if the cap wasn't sealing completely you would get lights coming on in the instrument panel because the fuel evaporative system would trigger them if the system isn't sealed correctly.

My friend: thank you very much for this valuable information! My check engine lights turned off!

 

[alkCo]

I also have this problem. I have tried genuine Toyota gas caps and aftermarket gas caps. None get a good seal. All just click but are still loose to the touch.

I am definitely getting CEL, too.

Can anything on the filler neck deform and cause mechanical interference that prevents the gas cap from screwing down?