Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0446: EVAP Vent System Performance: Description
This DTC tests the Evaporative Emission (EVAP) system for a restricted or blocked EVAP vent path. The PCM commands the EVAP canister purge solenoid Open and the EVAP canister vent solenoid Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the PCM commands the EVAP canister purge solenoid Closed and the EVAP canister vent solenoid Open. The PCM monitors the Fuel Tank Pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near zero in. H2O in a calibrated time, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent valves. See EVAP CANISTER PURGE & VENT VALVE RELATIONSHIP table.
| Control Module Command | EVAP Canister Purge Solenoid | EVAP Canister Vent Solenoid |
|---|---|---|
| ON | Open | Closed |
| OFF | Closed | Open |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.