Possible causes

– Missing Fuel cap
– Incorrect fuel filler cap used
– Fuel filler cap remains open or fails to close
– Foreign matter caught in fuel filler cap
– Vent control valve harness is open or shorted
– Vent control valve circuit poor electrical connection
– Faulty vent control valve

Tech notes

Before replacing any parts, try re-tighten the gas cap and clearing the code. If the cap or cap seal is damage replaced cap and clear the code.

When is the code detected?

– The P0446 codes triggered when an improper voltage signal is sent to ECM through EVAP canister vent control valve.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Possible a noticeable fuel odor caused by the release of fuel vapors

P0446 FORD Description

The Evaporative System (EVAP) canister vent control valve is located on the EVAP canister and is used to seal the canister vent.
This solenoid valve responds to signals from the Engine Control Module (ECM). When the ECM sends an ON signal, the coil in the solenoid valve is energized. A plunger will then move to seal the canister vent. The ability to seal the vent is necessary for the on board diagnosis of other evaporative emission control system components.
This solenoid valve is used only for diagnosis, and usually remains opened.

FORD Technical Service Bulletins for P0446 code