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Another P0455

dynamac

Full Member
Joined
Aug 9, 2011
Messages
19
I have an 04 with a newly rebuilt engine. Got the tighten gas cap on the cel then the check engine light came on. I have replaced the gas cap, the canister and valve under the truck by the spare and the valve on the engine. It would go out and then come back on. Replaced the fuel tank sensor and reset the coedes. went thru an entire tank of gas no light. #/4 of the way thru the second tank of gas and on comes the tighten gas cap and then the check engine light. I'm lost and don't know where to go from here. Any ideas would be greatly appreciated.
 
Which gas cap did you get, some folks have had problems with after market caps.
 
bought the ac delco locking cap. Just confused on how everything was fine for over 600 miles and then it comes back on. The tighten gas cap came on again this morning. At the same spot everytime on my way into work.
 
Double check the hoses that go from the tank to the filler for a leak.
 
Locking caps are known to be vulnerable to leaking air and causing these codes.  Try a non-locking cap.
 
bought a standard non locking cap and same problem. Check all the lines  on the tank and canisters. I can't find anything wrong. I have no idea what to do next.
 
I recently have been getting the P0455 code and the tighten gas cap warning.  After looking online, most people say it is the evap vent solenoid off of the charcoal canister.  When I was replacing that I pulled the lines off the charcoal canister and pieces of charcoal fell out of it, so I replaced the canister as well.  When I was driving it to work this morning, the warning came on again to tighten the gas cap and I have P0455 again.  Any idea on what to check now?  I applied 12v to the Purge valve on top of the engine and can hear it click so I don't think that is it.
 
Might be bad gas cap.
 
I should have mentioned that this didn?t happen until I replaced the vent solenoid trying to fix the issue of having trouble putting gas in the tank that is fairly common.
 
That came up on my 2005 1500 along with another code saying my ECT sensor was bad. When I replaced the sensor, both codes disappeared.
 
So as an update. It was fine for a week or so then the tighten fuel cap warning came on a couple of days ago. I bought a new Stant gas cap and reset the code and was fine a couple days again until yesterday when it came back on. I?m stumped at what to do now. I?ve verified that the evap and purge solenoids are both working correctly.
 
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