P0446 on Ford: How to Diagnose & Fix
Evaporative Emission Control System Vent Control Circuit
2 Ford models · 2 documented issues · $60-$350 repair
P0446 on Ford by model: symptoms, diagnosis and fix
A very common check-engine cause on the Explorer is an EVAP small-leak code, most often from a stuck or leaking canister purge valve, but also from the capless fuel filler seal, vent valve, or a loose/faulty gas cap. The purge valve controls fuel-vapor flow from the charcoal canister to the intake; when it sticks open or leaks it sets a small/medium EVAP leak code. It rarely affects drivability but will fail emissions testing and, if stuck open, can cause rough idle or hard hot-starts.
Common Symptoms
- Check-engine light with EVAP small-leak code
- Occasional fuel smell
- Rough idle or stumble if purge valve stuck open
- Hard hot restart
- Emissions test failure
How to Fix
Start with the cheapest checks: inspect/replace the gas cap and check the capless filler seal. Perform an EVAP smoke test to pinpoint the leak; replace the canister purge valve (or vent valve/canister) as indicated, then clear codes and run the EVAP monitor to confirm.
Sources for this issue (1)
The EVAP canister purge valve (purge solenoid) on F-150s commonly sticks in the open position, allowing raw fuel vapor from the charcoal canister to be pulled into the intake when it shouldn't be. This floods the cylinders with vapor — owners report a vehicle that cranks but won't start (or stumbles badly) immediately after filling the tank, then runs fine once it clears. A stuck-open or leaking purge valve, along with cracked/collapsed lines between the canister, valve, and intake manifold, is the most common trigger for P0496 (EVAP flow during a non-purge condition) and a frequent cause of P0455/P0442 large/small leak codes. Ford issued TSB 19-2132 covering loose EVAP hose connections on 2018-2019 trucks. The check-engine light is the usual first symptom; drivability impact ranges from none to hard-start/rough-idle. The real OEM purge valve part number is AU5Z-9C915-B (aftermarket cross-refs: Dorman 911-222, Standard CP1-prefix units).
Common Symptoms
- Check engine light with P0496, P0455, P0442, or P0446
- Hard start or no-start immediately after filling the fuel tank
- Rough or hunting idle that clears after the engine warms
- Slight loss of fuel economy
- Hissing or fuel-vapor smell near the engine
How to Fix
Verify with a smoke test before replacing parts — roughly 30% of P0455/P0456 codes are a loose or cracked gas cap, so reseat/replace the cap and clear first. If the purge valve fails to hold vacuum when commanded closed (it should seal), it is leaking and must be replaced. Inspect the rubber lines from the canister to the valve and to the intake for cracks/collapse and reseat loose connections per TSB 19-2132. After repair, clear codes and complete a drive cycle to allow the EVAP monitor to re-run. The purge valve sits near the throttle body/intake and is a quick R&R; expect roughly $25-$70 for the part plus labor.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- EVAP purge control valve (VMV, with fuel-tube support bracket) — 2017-2020 F-150 3.5L EcoBoost (2nd-gen GTDI)OEMJL3Z-9B325-D (replaces HL3Z-9B325-A / HL34-9B325-AB)Cross-refNOVAPARTS JL3Z-9B325-D (aftermarket copy)$69–$127
On the 2nd-gen 3.5L EcoBoost (2017-2020) the purge valve is sold by Ford as a valve + bracket unit under the 9B325 base number (catalog title reads 'Bracket - Fuel Tube Support, also includes VMV valve'). Ford catalog lists it for 2017-2…
- EVAP purge control valve (VMV, with fuel-tube support bracket) — 2018-2020 F-150 2.7L EcoBoost V6OEMJL3Z-9B325-CCross-refFANLIDE JL3Z-9B325-C (aftermarket copy)$76–$101
For 2015-2017 2.7L EcoBoost trucks Ford's catalog shows no standalone purge valve, only the FL3Z-9F945-C valve assembly (~$390) — those owners should verify by VIN at a dealer.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
P0446 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0446 mean on a Ford?
P0446 stands for "Evaporative Emission Control System Vent Control Circuit." This emissions code points to a problem in the evaporative emission (EVAP) system's vent control circuit, which manages the vent valve that lets the charcoal canister breathe and seals it during leak tests. The EVAP system captures fuel vapors from the tank to keep them out of the atmosphere, and the vent valve must open and close on command for the system to work and self-test. The code sets when the engine computer detects an electrical or performance fault with this vent valve or its circuit. It usually causes only a check engine light with no driveability change, but it does prevent proper EVAP leak monitoring. On Ford it is documented across 2 models: Explorer, F-150.
What are the most common causes of P0446?
The most common causes of P0446 are: Faulty EVAP vent control valve (solenoid), Wiring or connector fault in the vent valve circuit, Vent valve clogged with dirt, debris, or spider webs, Damaged or corroded vent valve connector, Blocked or pinched vent hose or filter, Faulty charcoal canister assembly, Faulty engine control module driver circuit. The specific cause varies by vehicle.
How much does it cost to fix P0446 on a Ford?
Published repair estimates on Ford range from $60 to $350 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0446 on a different make?
View P0446 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.