P0442 on a 2017 Ford Fusion Energi

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 Fusion Energi

Ranked from 1,030 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank pressure sensor / vent valve fault (gas-tank humming/honking, hard restart after refueling)
Medium severity
Several complaints describe a recurring humming/honking/sucking noise from the gas tank and stalling or hard-starting after fueling, consistent with a stuck vent valve or faulty tank pressure sensor holding the EVAP system at an abnormal vacuum.
Reported in 7 NHTSA complaints
Parts:fuel tank pressure sensor vent valve
2
Failing/stuck canister purge valve
High severity
Multiple complaints describe repeated canister purge valve (CPV) replacements and a valve documented stuck open, creating excess vacuum in the EVAP system.
Reported in 3 NHTSA complaints
Parts:purge valve
3
Loose or worn gas cap seal
Low severity
The most common small-leak trigger overall; verify the cap clicks fully and the gasket isn't cracked.
Common cause
Parts:gas cap
4
Cracked or brittle EVAP hoses/lines
Medium severity
Underhood heat and age crack rubber/plastic EVAP lines; smoke-test to pinpoint a small leak.
Common cause
5
Cracked charcoal canister
Medium severity
A hairline crack in the canister produces a small, hard-to-find leak; smoke test is usually needed.
Common cause
Parts:charcoal canister
6
Corroded or rusted fuel filler neck
Low severity
Rust-through at the filler neck is a common small-leak source on older vehicles; inspect visually and with smoke.
Common cause

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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