P0446 Code A Comprehensive Diagnostic Adventure for Mechanics

DTC P0446 or P1450 indicates that Self-Test has detected the Evaporative Emission Control System has excessive fuel tank vacuum. It could be as simple as the gas cap not seating correctly or could be, like in my case, the fuel line was rusted and leaking pressure and gas. I keep getting code PO466 Evaporative emission control system vent control circuit. It comes on for a couple days then goes off and then reappears again. What is a P0446 Code? Better yet, what the heck is a Evaporative Emission System Vent Control Circuit? Well I ran into this problem with my ... The P0446 code on a Chevy Silverado signals a problem with the EVAP system vent control circuit, usually due to a faulty vent control valve, ... So my truck is giving the code P0446 which is evap emission control system vent circuit malfunction. I have read a bunch of the posts on ... The P0446 error code signifies a problem with the evaporative emission control (EVAP) system's vent control circuit. Chased around a P0446 code for a week and finally fixed it today. 1. Replaced gas cap - code came back 2. Replaced Vent valve - $30 - code came back 3. Took ... DTC P0446 is a Type B DTC. ... DTC P0446 is a Type B DTC. ... An intermittent condition could be caused by a damaged EVAP vent housing, a temporary ... P0446: Purge airline is blocked or high flow resistance in the EVAP canister. 03-30-2014 10:55 AM ...