P0442 on a 2017 Ford F 150 Supercab

P0442 means the EVAP system could not hold pressure or vacuum during a leak test, but the leak is small.

Not your vehicle? See general P0442 info.

Most common causes on the 2017 Ford F 150 Supercab

Ranked from 1,066 NHTSA owner complaints filed for this vehicle.

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1
Capless "Easy Fuel" filler flap/seal failure
Medium severity
Multiple owners report gasoline vapor smell and fuel spraying back out at the capless filler neck, meaning the sealing flap isn't sealing fully and letting a small amount of tank vapor escape.
Reported in 2 NHTSA complaints
Parts:fuel filler neck seal
2
Purge valve stuck open (stall right after refueling)
Medium severity
One truck died repeatedly immediately after fill-ups, a classic sign the purge valve is staying open and pulling excess raw vapor into the intake, which also shows up as a small EVAP leak/flow fault.
Reported in 1 NHTSA complaint
Parts:purge valve
3
Cracked or brittle EVAP hose/line
Low severity
Heat-cycled rubber EVAP lines crack over time, leaking a small amount of tank vapor; smoke-test the EVAP system to find the leak point.
Common cause
Parts:EVAP hose
4
EVAP vent valve stuck partially open
Low severity
A vent valve that doesn't fully seat lets outside air leak into the EVAP system during the monitor's leak test.
Common cause
Parts:vent valve
5
Charcoal canister crack
Low severity
A cracked or corroded canister shell allows vapor to escape before it can be purged, tripping a small-leak code.
Common cause
Parts:charcoal canister
6
Fuel tank pressure sensor fault
Low severity
A drifting FTP sensor can make the PCM believe there's a small leak even when the system is sealed; check its reading against a scan tool at key-on.
Common cause
Parts:fuel tank pressure sensor

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0442 on your car still needs shop confirmation before any repair.

Common symptoms

Check engine light
Fuel smell near vehicle
Usually drives normally
Hard start after fueling in some cases

What to check before replacing parts

Tighten and inspect the gas cap

Look for: A cap that doesn't click to full tightness, has a visibly cracked or flattened seal, or is simply missing is the single most common cause of a small EVAP leak — rule it out first.

Smoke-test the EVAP system

Look for: Because this is a small leak, expect only a thin wisp of smoke or a faint hiss at one spot (a hose, seam, or valve) rather than an obvious cloud — look closely and take your time.

Check purge valve sealing

Look for: A purge valve that doesn't hold vacuum when commanded closed lets a small amount of air bleed through, which the system reads as a leak during its self-test.

Inspect hoses near the tank and engine bay

Look for: Look for small cracks, soft/collapsed spots, or a hose that has pulled loose slightly at a fitting — any of these can leak just enough to trip a small-leak code without an obvious fuel smell.

Verify vent valve operation

Look for: A vent valve that doesn't seal fully when commanded closed prevents the system from holding vacuum during its self-test, which reads as a small leak even with no physical leak in the hoses.

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Matching symptoms

Check Engine Light