P0442 on a 2017 Ford Focus Rs

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 Focus Rs

Ranked from 842 NHTSA owner complaints filed for this vehicle.

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1
Canister purge valve (CPV) stuck open / failing
High severity
Repeatedly cited as diagnosed cause (P1450 code, 'excessive vacuum in fuel vapor management system'); subject of Ford recall 19S22/19V515 for this platform. Confirm with a fuel-tank vacuum/EVAP smoke test.
Reported in 14 NHTSA complaints
Parts:canister purge valve EVAP purge valve hose
2
Fuel tank deformation / EVAP line damage from chronic excess vacuum
Medium severity
Owners report the fuel tank itself deforming and CPV needing repeated replacement, consistent with unresolved excess-vacuum EVAP faults on this platform.
Reported in 2 NHTSA complaints
Parts:fuel tank EVAP hose
3
Loose or damaged fuel filler (gas) cap
Low severity
Simplest and most common EVAP small-leak cause; check cap seats and clicks fully, inspect gasket for cracks.
Common cause
Parts:fuel filler cap
4
Cracked or brittle EVAP hoses/lines
Medium severity
Under-hood and under-body EVAP lines dry-rot and crack with age/heat, creating small vacuum leaks the PCM detects as EVAP faults.
Common cause
Parts:EVAP hose
5
Charcoal (EVAP) canister crack or saturation
Medium severity
A cracked canister housing or fuel-saturated canister fails to hold vacuum during the EVAP monitor test.
Common cause
Parts:EVAP charcoal canister
6
Faulty vent valve (canister vent solenoid)
Medium severity
A vent valve that won't seal properly prevents the EVAP system from holding the vacuum needed to pass the small-leak test.
Common cause
Parts:EVAP canister vent valve
7
Rusted or damaged filler neck
Low severity
Corrosion or physical damage at the filler neck can create a small unmetered leak path in the EVAP system.
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