Monitor Description
WARNING: This page is about a different car, the 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.
P0446-73: Vent valve stuck closed
In operation C, the vent valve turns on (closed) and the EVAP system pressure is then measured by the ECM using the canister pressure sensor to conduct an EVAP leak check. If the pressure does not increase when the vent valve is open, the ECM interprets this as the vent valve being stuck closed. In this case the ECM will illuminate the MIL and store this DTC.