Got a p0446 code on my GMC Sierra 1500 5.3 V8 4x4. Came back after doing everything

Question

put new gas cap, canister purge selenoid, vent valve solenoin servise bulliten ket and did not pass smog due to 3 inconplete zones not resetting, catalyst, Evap and o2 sensor. still did not pass and smog shop put new ECU computer in and toldme to drive to get same three zones to reset so it can be smogged. After driving a day now im getting a pending P0446 code. I was told everything checked out ok. Any sugestions before I take it back.

Answer 1

When you mention service bulletin kit is it # 02-06-04-0375? This is about replace evap vent valve vent valve solenoidassemble and Add/relocate filter box.. P0446 is EVAP vent system performance,if this is a pending code the catalyst will not run,neither will EGR,plus for the evap to run you need more than 1/4 tank fuel,use a smoke machine for the EVAP,look for a leak,,other than that use your nose,smell around for any gas fumes,