P0442 on a 2019 Ford F 150 Supercab Diesel
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 2019 Ford F 150 Supercab Diesel
Ranked from 953 NHTSA owner complaints filed for this vehicle.
- 1
EVAP purge or vent valve failure
High severityAn owner's fuel tank purge valve issue caused idling/performance problems and the tank was later found imploded, showing the venting path was blocked or malfunctioning.
Reported in 1 NHTSA complaint - 2
Cracked or ruptured fuel vapor line near the canister
High severityOne owner had a metal line running from the canister to the fuel rail crack and rupture, leaking fuel and vapor.
Reported in 1 NHTSA complaintParts:fuel vapor line - 3
Loose or damaged gas cap
Low severityThe single most common trigger for a small EVAP leak code; the cap fails to seal and lets vapor escape.
Common causeParts:gas cap - 4
Charcoal canister crack or saturation
Medium severityA cracked or saturated canister leaks vapor instead of containing it.
Common causeParts:charcoal canister - 5
Cracked or aged EVAP hose
Low severityRubber EVAP lines harden and crack with age and underhood heat, producing a small, steady vapor leak.
Common causeParts:EVAP hose - 6
Rusted or damaged fuel filler neck
Low severityCorrosion or physical damage to the filler neck breaks the seal path, causing a small detectable leak.
Common causeParts: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.