P0442 on a 2018 Ford Fusion

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 2018 Ford Fusion

Ranked from 429 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Purge valve / purge valve canister failure
Medium severity
Multiple owners had the purge valve (canister purge) replaced -- in one case twice -- and a mechanic specifically diagnosed a failed purge valve/flow valve (with DTC P1450) as the root cause of a stored EVAP fault.
Reported in 4 NHTSA complaints
Parts:purge valve
2
EVAP vapor leak in the fuel tank/vent system
Medium severity
One owner explicitly described an 'EVAP system leak' with a vapor leak preventing the vehicle from restarting normally after fueling.
Reported in 1 NHTSA complaint
3
Capless fuel filler neck seal/flap failing to seal (freezing in cold weather)
Low severity
One owner reported the capless filler's inner sealing flap freezing shut in sub-zero weather, indicating the filler-neck seal that normally keeps the EVAP system sealed was compromised.
Reported in 1 NHTSA complaint
Parts:fuel filler neck
4
EVAP vent valve/solenoid stuck open
Medium severity
A vent valve that won't fully close prevents the EVAP system from holding vacuum/pressure during the self-test, setting a small/large leak code.
Common cause
Parts:EVAP vent valve
5
Cracked or disconnected EVAP hose/line
Medium severity
Age-hardened or rodent-damaged EVAP lines under the vehicle are a common leak source.
Common cause
6
Cracked charcoal (EVAP) canister
Low severity
The canister housing can crack from age and road debris impact, opening a leak path.
Common cause
Parts:EVAP canister

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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.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Check Engine Light