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.
Diagnostic Aids
A short to ground causing the EVAP vent solenoid ON, will cause the vent valve to close. This will cause DTC P0446 to set.
ECM uses fuel tank pressure sensor to detect amount of vacuum pulled on EVAP system during leak diagnostic tests. Ensure fuel pressure sensor is not skewed by verifying FUEL TANK PRESS. SENSOR on scan tool is 1.3-1.6 volts with ignition on and fuel cap removed.
A faulty main relay will cause DTC P0446 to set.
Check for kinked, pinched or plugged EVAP vent solenoid hose, EVAP vent solenoid stuck in closed position or EVAP canister restricted.
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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.