Can a gas cap become faulty?** Not the problem! Help Please.

infernicus · **Posted:** Tue Oct 12, 2010 4:21 pm

I hope so..
So here's my story..
Last week, roughly about seven (7) days ago the "Check Engine" Light came on.
I drove straight to Advance Auto to Check the code, this is what he gave me;
------------------------------
P0456:
Definitition:
EVAP - small leak detected

Explanation:
The ECM has detected a large leak in the EVAP system during a system monitor test.

Probable Cause:
1. Defective, loose or missing fuel cap
2. EVAP canister broke, hose cracked or not connected
3. Purge or vent solenoid defective
4. Vacuum leak at engine
-------------------------------

So I removed and tightened the gas cap, unplugged the battery to reset the system. I had no issues, then about three days later I start my Jeep after it sitting for about 6 hours or so, after two fifty (50) mile trips, for a total of one hundred (100) miles. I instantly get a message come up, not the Check Engine Light, which surprised me, in the odometer space, where it usually tells you if the gate or glass is open, I get a "GASCAP" message.

So, I take it off, put it back on tightly, restart my truck and go on my way. Today about three days after the gascap, message my CEL come back on, I haven't gotten a chance to check the code, but I'm assuming it is related.

Any thoughts on this?
As always, thanks in advance.

mikey1273 · **Posted:** Tue Oct 12, 2010 4:39 pm

I can not say so much about gasser Jeeps since mine is a CRD but I had something like this happen with the Outback I used to have. check engince light would come on. I'd have it checked at Advanced. They would say the code ment the same as yours. they told me to remove the cap and put it back on thighten it till you hear 3 clicks. That worked for a few weeks then it happened again so I got a new cap and never had it happen again.

Part of every gas vehicle's emissions controls is keeping emmissions from the gas evaporating in. if the cap begins to not hold pressure this is what happens.

JeepinJarhead03 · **Posted:** Tue Oct 12, 2010 5:20 pm

absolutely, gas caps go bad all the time, sometimes it's the pressure valve, sometime's its a fault caused by the ratchet in the cap not allowing it to seat properly

new gas cap should resolve the issue with no further issue

devlish · **Joined:** Thu Sep 30, 2010 10:50 am **Posts:** 163

I was going to say YES as well... the pressure seal is bad. ^^ like mentioned... new gas cap should solve a reoccuring problem like this

tjkj2002 · **Posted:** Tue Oct 12, 2010 5:39 pm

You should always replace the gas cap every 2-3 years on a modern vehicle as it is a vital part of the emission system,heck it's only $12.

infernicus · **Posted:** Tue Oct 12, 2010 5:46 pm

Sweet, thanks guys.. Should I get from the dealer? or the caps from Advance/Autozone work fine?

tjkj2002 · **Posted:** Tue Oct 12, 2010 5:51 pm

infernicus wrote:

Sweet, thanks guys.. Should I get from the dealer? or the caps from Advance/Autozone work fine?

They all work the same and seem to last the same amount of time.

mikey1273 · **Posted:** Tue Oct 12, 2010 7:49 pm

and yes its not an expensive item. I think the Cap for my Outback was under $15 from the Subaru dealer. Fuel caps are not expensive unless you need a locking one with a key then the price can go up.

Rotten Ollie · **Posted:** Tue Oct 12, 2010 10:07 pm

I had the same problem 2 months ago.....same code, replaced the gas cap and no problem since, went to autozone even bought a locking one. Cant remeber what i paid, it wasnt much

NanoCar · **Joined:** Wed Sep 22, 2010 3:43 am **Posts:** 12

infernicus wrote:

Sweet, thanks guys.. Should I get from the dealer? or the caps from Advance/Autozone work fine?

Agree with the rest.. replacement would be the solution.. I think those work fine.. lately I got some Jeep Parts from them.. goodluck!

infernicus · **Posted:** Sun Oct 17, 2010 2:41 am

Sooooooo, I bought my 10.99 gas cap from Autozone.
Tonight, at 1:00am, I start my truck, begin to take off, and "BING BING BING" .. I get the GASCAP message again.

Any ideas?? Starting to get worried.

infernicus · **Posted:** Mon Oct 18, 2010 7:41 pm

Soooo, again :cry:

My CEL comes on.. It is P0456 again.

Any ideas what it could be?
Would it be something taken care of under warranty at the dealer?
Or should I just bring it to my mechanic?

tjkj2002 · **Posted:** Mon Oct 18, 2010 7:51 pm

infernicus wrote:

Soooo, again :cry:

My CEL comes on.. It is P0456 again.

Any ideas what it could be?
Would it be something taken care of under warranty at the dealer?
Or should I just bring it to my mechanic?

Are you still under the 3/36 warranty? If not your paying for the diag since the EVAP system is not covered by the powertrain warranty.

The best way to find the problem is now to have a smoke test done,expect $100-$150 for that test.Oh and besides the gas cap all the other EVAP parts are very expensive.

Blue KJ in PA · **Posted:** Mon Oct 18, 2010 9:00 pm

Slide under the rear and look at the vent lines...hard plastic...and check the rubber hose joints...mine were cracked. Also the ones up in the engine bay by the firewall. Replaced all those and the CEL code went away.

jeep4life7 · **Posted:** Mon Oct 18, 2010 11:18 pm

i have the same problem i got a new sensor and i was going to get a gas cap or new one u know wat i mean. but idk wat would be the next step?

Albert · **Posted:** Mon Oct 18, 2010 11:30 pm

Hi Dean. Check all your emissions hoses going into the canister by the gas tank and then check the ones under the hood by the pump next to the battery and look for a unhooked/cracked or broken hose. Then if you can't find anything you will have to revert to what tjkj said.

infernicus · **Posted:** Mon Oct 18, 2010 11:45 pm

Yikes.
Well I have the extended warranty, 7 year/70k miles.
Would it be covered under that?
I'll have to crawl under tomorrow.

infernicus · **Posted:** Wed Oct 20, 2010 4:07 pm

I took a look at everything I could. Nothing appeared cracked or disconnected.

martin99 · **Joined:** Wed Sep 29, 2010 9:24 pm **Posts:** 9

I had a similar problem a few years back on a different vehicle (f150) where the filler neck for the gas cap was plastic, which was cracked. If that is your problem all the new gas caps in the world won't save you, however the filler neck should be pretty cheap. I'm not sure how the filler is attached on a KJ (never bothered to look) but on an f150 it's a permanent part of the fuel tank, still cheap but talk about a PITA to replace. Might be something to check although probably a rare problem.

infernicus · **Posted:** Wed Nov 17, 2010 12:37 pm

HEY!
I forgot to update this.. (my CV busted, and I wasn't driving my Jeep for almost two weeks, so this was put on the back burner.)
BUT! Get your gas cap from MOPAR. I bought one from Autozone and turned out it didn't solve it, when I brought it to the dealer they wouldn't warranty it because I didn't have the original.. (lame)
When I used the gascap from Mopar, my light went away after a couple of cycles, and hasn't come back since.

Thanks everyone!

Can a gas cap become faulty?** Not the problem! Help Please.

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