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Check engine light/gascap reading on panel

151K views 41 replies 12 participants last post by  RHD SuperSub 
#1 ·
Ok so I got this issue going on where my check engine light keeps coming on and it is displaying gascap on the instrument panel. I have reset this about 5 times now and it keeps coming on.

So here is what I did. First it wasn't saying gas cap it was just a check engine light. I read it with the flashpaq and it had a small evape leak code. I immediately checked the gas cap and it did feel a little loose. I tighten it and cleared the code.

It came back on again so I then thought maybe it was ba bad gas cap or a leaking seal around the gas cap. I went and bought a new gas cap from advance. Put it on and cleared the code with the flashpaq. Check engine light came back on but started reading gascap on the instrument panel this time.

So I then checked all the evape lines for cracks, none, looked at the canister all good, cleared the code and it came back on the same way ,check engine light, gascap , code reads small evape leak.

Today I done a smoke test on it and no signs of any leaks. Its driving me nuts. I put the old gas cap back on since the on from advance wasn't helping. I'm thinking about getting a mopar one and seeing what that does. Anybody got any advice on what this can be and what I can do it fix it. Thanks

Jamie
 
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#3 ·
This can be a PITA, and it'll cause you to pull your hair out and beat your head against the wall.

Personally I'd get a MOPAR gas cap and see if that does anything for you.

My wife's Challenger has an intermittent issue with the gas cap throwing the CEL. What she does is remove the gas cap and reinstall. What is strange is that when she buys a certain brand of gas it usually doesn't show up, but it will with another.

She does have an aftermarket (Stant) gas cap which I think is the route of her issues, but she refuses to let me buy a MOPAR cap.

If a MOPAR cap doesn't fix the issue, I would consider taking it in to the dealer or your favorite indy mechanic.

good luck

Exco
 
#5 ·
I have same problem. Will look at those items soon now that it is Warner outside. Does anyone think it is mileage related?
 
#10 ·
Wanted to update this and let you know where I'm at with it. So I had cleared everything and reinstalled the stock gas cap. Then I went almost filled up on gas had right at 300 miles until empty. Everything stayed off gascap and check engine light until I got to around 110 miles until empty and the check engine light came on and had thrown a large evape leak code this time. I cleared it again last night and put more gas in it and I have driven about 60 miles since the reset and nothing has pop on yet.

Still a puzzle to me. About drive me nuts trying to figure this out. If anybody has any ideas shoot them my way.
 
#11 ·
I battled a similar GASCAP fault with my 2007 Chrysler for two years. New gas cap (two of them), two new fuel tanks, smoke leak test, etc. They eventually replaced the ESIM switch AND the filter upstream of it. They had replaced the switch one time but the new one went bad after a few months due to the upstream filter being full of moisture and things.

Mine was also throwing a P0456 code now and then, in addition to the GASCAP fault.
 
#16 ·
My 2015 JKU has less than 5900 miles on it and the dreaded check engine light came on. Flash cal says it's the P0456 code. I tightened the gas cap and cleared the light. Hoping this will do the trick given how new my vehicle is. Jamie, do you have an update on how you resolved your issue?
 
#17 ·
No luck yet boss. I changed the gas cap and the sensor on the evap canister still no luck. I just been clearing it but I'll probably try the O2 sensor next. I smoked it at my buddies shop and I haven't got a leak. Still a work in progress, hopefully I can figure it out. It stays off for 3 or 4 days and then first the gascap light, then about 2 days later the check engine light will come on.

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#18 ·
Jamie, be sure to check the lines the are next to the battery, I had one run a hole and gave me the same error. That was of course after I changed the gas cap and replaced the evap canister
 
#21 ·
I definitely check those as well. I did not realize their were any over there. All the lines from the gas to evap look good. I'll check again tomorrow when it's light out. I would really like to get it solved but I have been dealing with it for the most part.

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#25 ·
Thought I'd give you a update, today the check engine light cleared itself and the gascap light cleared. Not sure what's going on, the only thing I have did different was I reprogrammed the superchips flashpaqs tuner to run 87 octane instead of the 93 octane tune. I did the reprogram two fill ups ago and the check engine light and gas cap light was on while driving into work but I just noticed that both have turned off. Hopefully it will not come back on.


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#29 ·
Does that grease require re applying periodically ?
 
#36 ·
I'm going to give her shin-etc a try then O2 sensors. I got a fuel cap on mine, and have been through two Mopar gas caps and one advance one. I cleared mine on Tuesday and today got the gascap light after the gas got down around 100 miles till empty. I have noticed if I keep the gas above half a tank it seems to stay off, but as soon as it gets to a 1/4 tank or below it wants to trip everything. It could just be coincidence as well but last time I was keeping it above half a tank and it stayed off for three weeks until my son drove it and for the gas down below a 1/4 of a tank and as soon as I got in and started to go bam, gascap followed by 3 days later, check engine. On Tuesday the check engine light was on and the gascap words in the info center but when I checked the codes it wasn't reading any codes . Weird, I took it by advance so they could check it and they couldn't pull one either.

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#37 ·
Being a dumbass, I left the gas cap on the pump TWICE no less. Once in my JK and once in my wifes JKU. I drove about 200 miles without a cap (didn't notice until I refueled) and never got a light. Also the same thing in the other one after about 100 miels, and still no light. The second one I stuck a rag in the opening try to help keep the evap down, no light also. I dunno
 
#39 ·
This sounds interesting as I am a habitual offender of this practice. Can you elaborate?
 
#41 ·
Thanks for the follow up.
 
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