P0442 on a 2016 Ford Focus

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 2016 Ford Focus

Ranked from 1,187 NHTSA owner complaints filed for this vehicle.

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1
Canister purge valve (CPV) stuck open/failed
Medium severity
By far the dominant documented issue on this exact vehicle: a stuck-open or leaking CPV (subject of Ford recalls 18S32/19S22 and campaign 24N07) prevents the EVAP system from holding vacuum, repeatedly triggering small-leak codes, hard restarts after fueling, and stalling across a large number of owner reports.
Reported in 14 NHTSA complaints
Parts:canister purge valve
2
Deformed/collapsed fuel tank from failed purge valve
Medium severity
Owners here report the fuel tank being found dented or collapsed after a stuck-open purge valve prevented the tank from venting properly during a recall repair — this directly disrupts the EVAP system's ability to seal and pass its leak test.
Reported in 2 NHTSA complaints
Parts:fuel tank canister purge valve
3
Loose or worn gas cap / capless filler flap seal
Low severity
A cap or capless filler-neck flap that doesn't seal fully is the most common small-leak trigger industry-wide; check for a proper click/seal and inspect the flap seal for debris or wear.
Common cause
Parts:fuel cap
4
Cracked EVAP hose or fitting
Medium severity
Age-hardened EVAP lines under the hood or near the tank crack and produce a small, steady leak the monitor detects.
Common cause
Parts:EVAP hose
5
Cracked charcoal canister
Medium severity
A physically cracked canister shell is a common small-leak source, particularly after road debris impact or age-related brittleness.
Common cause
Parts:charcoal canister
6
Corroded/rusted filler neck
Medium severity
Rust-through at the filler neck opens a persistent small leak path; more common in road-salt climates.
Common cause
Parts:fuel filler neck

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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