[shifty]

I feel like I'm being noisy on the forum since coming back. Sorry. Lots of stuff hitting at once and I have a rare increase in free time which can end any second!

Truck: 1998 Sierra, 5.7L, 90k miles, throwing P0446 code alone.

Recent mechanical work done (last 8 months):

• Stant locking gas cap installed (September 2018)
• SeaFoam top-end cleaning (January 2019)
• A/C compressor and serpentine belt replaced (April 2019)

Let me say up front:

• Gas cap seems the obvious culprit to me here although that was 7 months ago ...
• Still, last night I cleared the DTC and reinstalled the OEM gas cap just in case ...
• But strange it started shortly after AC work, being the compressor is next to EVAP can and all ...
• So I checked hoses to EVAP can, hoses attached to intake top-end plastics, airbox, all look OK
• The truck was never really driven in overly dusty environments during its life, if someone is headed down that path.

I'm thankful GM's EVAP systems seem pretty simple. Sadly, I don't have a diagnostic tool that will allow me to watch tank pressure sensor output or jigger any valves so I'm flying blind here.

I'm curious how often do the EVAP cans or tank pressure sensors go out? Seems like they're cheap ($120 combined) to replace.

Anything else I should be looking at? Which hoses should I absolutely check, other than the two attached to the EVAP can and the ones attached to black intake plastics?

Any thoughts on where to start with testing, knowing all I have is a cheap Ancel AD410 ODBII tool?