Check Engine Codes P0443 and P0458

Bryan Hughes · January 14, 2020

Hello forum folks, I apologize in advance for what I'm sure is an easy answer, but I'm about to lose my mind. I purchase a 2015 GMC Canyon (3.6L V6 All Terrain) last weekend. One day out a check engine light came on, it was the gas cap not on tight. The technician at the dealership didn't put it back on right when I bought the truck, my bad for not checking. But the next day I get two codes, P0443 and P0458... As a former Ford Escape owner, Im painfully familiar with the EVAP purge valve needing to be replaced. But I couldn't believe something like that would go bad so quickly. After all, I just bought the truck two days prior...

Anyways, to error on the side of caution, I purchased a new EVAP purge valve and installed it myself. I'm sure most people on these forums would agree its pretty easy.

So almost a full day goes by with no light, then as I'm driving home from work, there they are AGAIN! The same two codes... I have a code reader, so I clear them. Drive ten miles, BOOM back again... I even tried disconnecting the negative post from the battery to do a hard reset. That seemed to work, took the truck for a small drive, turned her off, then when I started it back up, there's the check engine light with the same two codes again. So at this point I'm at a loss and desperate for any advice that would help keep me from having to take it in to a mechanic. Please and thank you!

Edited January 14, 2020 by Bryan Hughes

davester · January 14, 2020

First, it is possible to get parts that are bad, or fail soon after installation.

Second, a code related to a specific sensor does not necessarily mean that sensor has failed. Typically, the diagnostic procedure for each code listed a number of different things that may cause that code to appear.