P0442 on Ford: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Small Leak)
4 Ford models · 4 documented issues · $20-$450 repair
P0442 on Ford by model: symptoms, diagnosis and fix
Owners report extended cranking, rough idle, or stalling shortly after refueling due to an EVAP canister purge valve that sticks open and floods the intake with fuel vapor. This failure mode is documented across Ford applications and appears in Transit Connect owner reports and service literature addressing purge valve performance. The condition often triggers EVAP-related DTCs and can worsen over time.
Common Symptoms
- Hard start immediately after refueling
- Rough idle or stumble after fill-up
- Occasional stall when coming to a stop
- Fuel odor near engine bay
- Check engine light on
How to Fix
Replace the EVAP canister purge valve/solenoid and inspect EVAP lines for liquid fuel contamination. Clear codes and verify proper purge operation with scan tool commands; advise against topping off the tank to reduce recurrence risk.
Sources for this issue (1)
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 (2)
On the S550 Mustang (both 2.3L EcoBoost and 5.0L GT), P0442 (small EVAP leak) is commonly blamed on the canister purge valve solenoid. EcoBoost owners report installing a purge valve that immediately sets a light, then a second or third valve that clears it; however, Ford's SSM 50306 states that returned purge valves tested fully functional and directs technicians to run the FDRS EVAP leak and purge-valve tests before replacing parts. Other common causes are a capless Easy Fuel filler inlet that is not sealing (the car may display a 'Check fuel fill inlet' message) and cracked/split EVAP hoses or a leaking vent valve near the charcoal canister. Habitually topping off the fuel tank after the pump clicks off floods and damages the purge valve/canister, accelerating the failure.
Common Symptoms
- Check engine light on
- No drivability change in most cases
- Possible faint fuel smell
- Slightly reduced fuel economy if purge valve stuck open
- 'Check fuel fill inlet' message in some cases
How to Fix
Check the capless fuel filler inlet for debris or a flap that is not closing first. If the code persists, smoke-test the EVAP system to pinpoint the leak (Ford directs running the FDRS full-system EVAP leak test and purge valve leak test before replacing the valve); if the purge valve fails, replace the canister purge valve solenoid with the latest Ford part number, then inspect EVAP hoses and the vent valve for cracks. Stop topping off the tank to prevent repeat failures. Clear codes and complete a drive cycle to confirm the readiness monitor passes.
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 or partially connected EVAP vapor lines (DTC P04F0/P144C) on 2018-2019 F-150s with the 2.7L or 3.5L EcoBoost. The check-engine light is the usual first symptom; drivability impact ranges from none to hard-start/rough-idle. The 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.
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Sources for this issue (1)
P0442 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 P0442 mean on a Ford?
P0442 stands for "Evaporative Emission Control System Leak Detected (Small Leak)." This emissions code means the evaporative emission (EVAP) control system has detected a small leak. The EVAP system seals the fuel tank and captures gasoline vapors, routing them to be burned in the engine instead of escaping into the air, and the computer periodically pressure- or vacuum-tests the system to confirm it's sealed. A small leak the size of about a 0.040-inch hole will set this code. By far the most common and cheapest cause is a loose, damaged, or missing gas cap, so that's the first thing to check, though any cracked hose or worn seal in the system can also trigger it. On Ford it is documented across 4 models: Transit Connect, Explorer, Mustang, F-150.
What are the most common causes of P0442?
The most common causes of P0442 are: Loose, damaged, or missing fuel filler cap, Worn or cracked gas cap seal, Cracked or disconnected EVAP hose or line, Faulty purge valve or vent valve, Damaged O-ring or seal at the fuel tank or filler neck, Small crack in the charcoal canister, Leaking fuel tank sending unit gasket. The specific cause varies by vehicle.
How much does it cost to fix P0442 on a Ford?
Published repair estimates on Ford range from $20 to $450 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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.