P0446 GMC Sierra 1500
EVAP Vent Control Circuit Malfunction · Powertrain Code · Low · Repair: Easy
What is P0446?
The EVAP vent control circuit has an electrical issue preventing proper vent valve operation.
When the GMC Sierra 1500 triggers code P0446 (evap vent control circuit malfunction), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the GMC Sierra 1500.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your GMC Sierra 1500.
Common Causes on GMC Sierra 1500
- Failed EVAP vent solenoid (the number one cause on GM trucks and SUVs)
- Vent solenoid wiring damage from road debris or corrosion
- Blocked vent path from dirt, mud, or insect nests in the vent line
- Charcoal canister vent port clogged
Symptoms
- Check Engine Light on
- Difficulty refueling (pump clicks off repeatedly)
- Possible fuel smell
- Tank may feel pressurized when opening gas cap
Notes for GMC Sierra 1500
GM trucks and SUVs are notorious for EVAP vent solenoid failures — the part is under $30 and mounted near the rear of the vehicle by the charcoal canister.