Question

Engine code P0446 on a 1998 GMC Sierra 5.0L, how do I fix the code? Evaporative emission system vent control circuit

Answer 1

Hi there, The most common cause for the code is the actual vent control valve. These fail quite often on most models. It's mounted under the truck in the frame near the gas tank. Depending on the model you have it could also be in the frame on the cross bar and not the side rail.

Answer 2

P0446 GMC Code - Evaporative Emission Vent System Performance
Read more: https://www.autocodes.com/p0446_gmc.html