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P442 and P455 Engine Codes

D

djb

New member
I tried searching for these codes, but I cannot seem to find much on them. I have a 2008 GXP. I keep drawing these codes. I reset them and they return. I have tried replacing the gas cap as I was getting an error in the DIC to check the gas cap. That did not help. Any suggestions on beginning to diagnose the root cause for the codes? As always, I appreciate anyone's input.
 


I can't look into it much at the moment. But try googling "GM DTC P04XX" with the XX being the last two digits of your codes. I found a lot of info. Work...holds me back though.
 
They are EVAP codes ...I'd check the EVAP purge solenoid if you haven't...or the vac lines running to it. They are a common failure on plenty of GM cars...had the issue on my silver GT and my old Cobalt as well.

Secondly, did you replace the gas cap with an OEM one or an aftermarket one? Because I've ran into the aftermarket ones being pretty much junk...for reference, my Cobalt EVAP solenoid was like $40...not sure on the GXP.
 
I will search and see what comes up.

I did replace with a GM OEM gas cap. I was hoping that would be the issue, but alais is was not.:mad:
 
DTC P0442: Evaporative Emission (EVAP) System Small Leak Detected

DTC P0455: Evaporative Emission (EVAP) System Large Leak

trouble tree is kind of large for the P0455
 


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