P0442 on a 2012 Ford F 150 Supercab
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 2012 Ford F 150 Supercab
Ranked from 1,717 NHTSA owner complaints filed for this vehicle.
- 1
Stuck or faulty EVAP vent/purge valve causing pressure buildup
Medium severityOne owner reported gasses building up in the tank and causing an audible noise, consistent with a vent/purge valve not cycling correctly.
Reported in 1 NHTSA complaint - 2
EVAP line leak indicated by a fuel odor
Medium severityOne owner reported a strong fuel smell from the vehicle coinciding with an electrical/no-start fault, consistent with a leaking EVAP line near the tank or fuel system.
Reported in 1 NHTSA complaintParts:EVAP hose - 3
Loose or faulty gas cap
Low severityThe most common small-leak cause; check the seal and that it clicks fully closed.
Common causeParts:gas cap - 4
Cracked or brittle EVAP hoses/lines
Medium severityAge and heat-cycling crack rubber EVAP lines, producing a small leak the self-test detects.
Common causeParts:EVAP hose - 5
Charcoal canister cracks or saturation
Low severityA cracked or fuel-saturated canister can't hold vacuum during the EVAP monitor's test.
Common causeParts:charcoal canister - 6
Rusted or damaged filler neck
Low severityCorrosion at the filler neck creates a small unmetered leak path.
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.
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