07 Yukon error code P0455 coming back after replacing vent valve

[jf858]

Hi Everyone!

First of all thank you for accepting me as a member on this awesome forum.

As you see i am a new member, as well as a new owner of a used 2007 Yukon, i found some issues with my truck, and as well looking to upgrade some features myself.

So not to overwhelm my dear friends on this forum i will ask 1 question at a time. Ok so here i go.

after driving my truck for a few weeks i got the check engine light, went to a mechanic across from my workplace, the diagnosis was a P0455 - Gross leak.

so he recommended (and did) a smoke test, he showed me a leak at the rear of the vehicle, and said that it needs a new "vent Valve Solenoid".

so i went to the local dealer and bought the part, swapped it out myself in the matter of an hour and went back to him to clear the check engine light.

But unfortunately the light came back on after a week, this time i went to my friend (who works at a school bus shop) and his computer gave the same code P0455

so before going back to the original mechanic for another smoke test or whatever, i would like to ask you guys what you think could be the issue here?

Thanks so much in advance.
Joel

 

[farphle]

I had this issue on my 07 Yukon after having the fuel pump replaced by the dealer. I replaced the vent solenoid, gas cap, and purge valve. Turns out it was one of the hoses that attaches to the fuel tank. Dealer forgot to re-connect it.

 

[jf858]

Thanks phaplre.

I guess i should take a second look to see what i missed when i changed the solenoid.

My next step would be another smoke test to rule out another leak.

Thanks guys.

 

[jf858]

Ok so a little update.

I went back to the mechanic for another smoke test, this time the smoke came out of the end piece of the vent valve assembly, a small black plastic box, it looks like a filter.

Could someone suggest what the issue might be? could the part be defective? or is the canister not getting the required voltage?

Please someone enlighten me.

Thanks.
JF

 

[nellyvanos]

i had the same code P0499 and P0455 ..which with my scan tool showed me they were related..purge selonoid leak ...so i switched out all three parts the vent ,gas cap and valve...code was gone even without smoke test and it has been gone since....check you gas cap...when u do the smoke test as well it could be the last bit of your problem ....plus all these parts are super cheap ..dont get ripped off

 

[jf858]

Ok. So I changed the gas cap ( bought at dealer for $40) cleared the CEL and so far it didn't come back on after 200 miles. Let's hope it stays that way. Thanks all for your help!

 

[rockenthebowtie]

Is he commanding the vent valve shut when performing the smoke test if not smoke will leak all day long if not commanded shut when doing smoke test also might want to try the purge control solenoid to see if the fuel tank pressure sensor drops to a negative reading and holds once purge valve is commanded off.. the purge control solenoid is pulse with modulated in percentage so with engine running vent valve commanded shut command purge valve to 100% with the scan tool hopefully his scan tool had funtional operations

 

[jf858]

I bought an OEM gas cap, cleared the CEL and all is fine now. Looks like it was a misdiagnosis of my mechanic.

Thanks all for your help!

 

[jf858]

After a few weeks code came back, I cleared it and now I have the P0496 code.
Any suggestions?