Gas Cap Fault, We have a gas cap leak fault but the gas cap was replaced and did not make a difference. We did a smoke test and the only smoke we saw was out of the fresh air assembly next to the fuel fill hose. Don't know if that should have happened but that was the only leak. Also I can't find where the fuel vacuum pressure sensor is. Any help would be great.
gas cap fault but not gas cap
- Thread starter agood01
- Start date
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CheddarGau
Full Access Member
You try to pinch of the hose at the vent valve hose and see if that will pressurize the system and check for leaks that way. What year of KJ do you have?
My 2007 has the same "gas Cap" code in the odometer block but also getting codes P0456/7 for evap
This is a problem with lots of 2007 Libertys. Even the dealer can't give a reason it happens. They will do a factory computer check but they said most parts are no longer available through them. They did change that gas system vents in 2007.
I have a 2012 KK. Got the same code ended up changing my fuel tank expansion canister which solved the issue. 30 bucks at advance auto. Located directly next to and actually resting up against the battery.
Puddle Jumper 2.0
New Member
I have a separate thread going on this as well. I replaced the gas cap, purge control solenoid (next to battery), the switch on my evaporator canister by gas tank all with MOPAR parts and erased all codes with my scan tool and as soon as I started the rig that stupid “GASCAP” message popped up on my dash in the odometer field! My next idea is to pull the rear splash shield and inspect the filler tube assembly that goes into the gas tank…… I am tempted to run the tank down to nothing (maybe one or two gallons of fuel) and drop it down to get better access for inspecting vac lines back there. I am wondering if there is some debris that has worn a hole in one of the lines??? Even though this jeep has lived all of its 180,000 mikes of life on paved roads with next to nothing on gravel roads with the exception of the “chip seal” replacing that DOTs live to put on our roads instead of actually fixing them….. as I move through this I will post each step of the way. Thanks to all!!!
Puddle Jumper 2.0
New Member
UPDATE: My light is off now. Apparently mine was the valve on my evaporator canister (left rear of vehicle up high in front of gas tank). I used my code reader to reset all the evaporator codes and the gas cap message returned immediately after the repair. I moved on to other items after all the cheap and easy to get to things did not resolve it. After viewing one post on here about some corrosion at the top of the fuel sending unit I picked up a new MOPAR fuel pump/filter/level unit and after about five years of the filler neck puking gas back out at EVERY refill (if not slow and careful attention was paid when hearing full) I also grabbed a new MOPAR gas tank filler assembly (New Old Stock from EBay) my wife took the KJ over to Wenatchee Washington to attend the Relay for Life held at Eastmont High School’s track to celebrate another year of being cancer free and the light stayed off the whole time. Now with close to 200K on it I am going ahead with dropping the tank and installing the new parts along with a new MOPAR gas tank wiring harness too and will closely inspect EVERYTHING while the tank is out but I wanted to mention, and now recall someone posting , that ignition cycling of “X” amount of times may be needed to get some codes to clear completely. So, even after I clear codes now (on all my rigs) I will be cycling my ignition on and off atleast a dozen times or so before I accept that a code is still valid. My issue must have been either the o-ring that seals the valve to the evaporator canister or the valve itself as I did not replace the actual canister. Aftermarket evaporator canister will come with the valve and admittedly the cost of the MOPAR valve alone was slightly more but factory parts have given me close to 200K miles so when I can I will replace them with the same parts that got me where I am now. Anyway, those evaporator codes can be a pain to track down and I started right next to the battery replacing components (after the gas cap, which from what I read on here is RARELY the source of the “gas cap” message on the dash) and this is what worked on my 07 Sport. A big THANK YOU!!!! to all who replied with ideas and direction it was all very much appreciated!!!!
