P0442 on a 2018 Ford Focus Bev

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 Focus Bev

Ranked from 743 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Canister Purge Valve (CPV) stuck open (NHTSA Recall 18V-735)
Medium severity
This is by far the dominant issue in the complaint set for this vehicle: a CPV that sticks open (with PCM software slow to detect it) causes stalling right after refueling, an inaccurate/erratic fuel gauge, hard restarts, and repeat check-engine lights with EVAP codes (P0456, P1450, P144A) - the exact pattern described in the recall bulletin.
Reported in 17 NHTSA complaints
Parts:purge valve
2
Deformed fuel tank from excess vacuum (secondary effect of a stuck-open CPV/blocked vent path)
Medium severity
Ford's own recall bulletin for the CPV defect notes that a stuck-open valve can create excessive vacuum in the vapor system severe enough to deform the fuel tank, which itself can then leak and re-trigger the code.
Reported in 1 NHTSA complaint
3
Loose or damaged fuel filler cap
Low severity
Always check first for a small leak; a cap that doesn't seat or seal fully will set this code.
Common cause
Parts:fuel cap
4
Cracked or chafed EVAP vapor line
Medium severity
Small leaks between the tank, canister, and purge valve fail the leak-detection monitor; smoke-test to locate.
Common cause
Parts:EVAP hose
5
Cracked charcoal canister
Medium severity
Hairline cracks in the canister housing produce a small, steady leak that fails the monitor.
Common cause
Parts:charcoal canister
6
Vent valve stuck open or leaking
Medium severity
The canister vent valve must seal for the EVAP monitor to build vacuum; a leaking vent valve is a common small-leak cause independent of the CPV recall.
Common cause
Parts:vent valve

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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