Hi scottt
I have a 2006 gmc envoy denali and had the check engine light come on yesterday put the scan tool on it but no codes but on the dash read tighten gas cap well checked gas cap and it was bad so went and bought a new 1 put it on and used the scan tool to reset the engine light drove back home everything fine drove to work later that night still fine well on my way home from work the smorning got the message across dash again to tightin the gas cap no check engine light this time at least not yet any idea of whats going on.
You’ll need a higher level scan tool to read codes. Try visiting your local auto store who should be able to scan your ECU for free & then post the codes here.
Ok being i cleared the check engine light with my code reader do i need to wait for check engine light to come back on or will they be able to pull codes still
Tighten Gas Cap should’ve triggered an EVAP code which would be stored in the ECU. However, if you want to wait till the CEL turns on, that’s completely up to you, if the car drives normally otherwise.
It cold be that it has an EVAP leak somewhere and the computer is mistaking blaming it on the gas cap.
You'll need to have a scan tool with enhanced diagnostics. EVAP readings might be in a zone between normal and tripping a code.
Ok thanks CEL just came back on today so gonna take it to have it scanned
Ok got the codes looked them up already but wanna get your guys opinion codes are u1064,p0455,p0455 yes got the same code twice
They seem potentially related, at least at first glance: P0455 has to do with a large EVAP leak, and u1064 has a number of possible causes, but one stood out, as possibly connected:
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The reason of U1064 OBD-II Engine Trouble Code is Ambient Air Temperature Sensor Circuit Low.
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While this could be an instance where correlation does not equal causation (the two happen at the same time, but there's no direct cause and effect), it's also possible that a large EVAP leak might generate an ambient air temperature fault, perhaps passively or actively (by damaging the sensor). But that's far from certain.
You're going to need more diagnosis, and a bit of tinkering perhaps to rule out/implement all the cheap fixes, such as new spark plugs, that might generate a u1064 code.
Good luck.
None of what you wrote even comes close to what i read online besides the large evap leak from what i read online the u code was either ignition switch going bad which is common in these gmcs or battery connections are not connecting properly now for the p0455 could a going bad fuel pump cause this code
Here's the info that I read on the codes: (Links) http://u1064.enginetroublecode.com/gmc-envoy
P0455: https://www.trailvoy.com/threads/p0455-evaporative-emission-system-leak.95821/
https://www.trailvoy.com/threads/replacing-purge-valve-control-solenoid.76766/
Good luck!
Thanks for the help ill have to do more digging cuz my gmc has none of those conditions from the link starts up run and drives perfectly to me so im not sure only issue i have is when i start it you get a loud humming sound coming from rear end but goes away after a few seconds maybe used wrong word there (humming) but its difficult to exsplain i guess
Good luck in your investigation.