P0442 on a 2016 Ram 1500

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 Ram 1500

Ranked from 1,508 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank strap corrosion causing tank to sag and stress EVAP lines
High severity
A large cluster of owners report the front fuel tank strap rusting through and letting the tank sag or drop -- a documented defect adjacent to Ram's tank-strap recall -- which can stretch or crack the EVAP lines routed near the tank.
Reported in 6 NHTSA complaints
Parts:fuel tank strap
2
Restricted or corroded fuel filler neck / vent path
Medium severity
Owners describe the fuel nozzle repeatedly sticking or shutting off early when fueling, a classic symptom of a restricted filler neck or EVAP vent path that can also register as a small leak.
Reported in 2 NHTSA complaints
Parts:fuel filler neck
3
Loose or worn gas cap
Low severity
A cap that doesn't seal is the most common small-leak trigger and should be checked first.
Common cause
Parts:gas cap
4
Purge valve failure
Medium severity
A purge valve that leaks or won't seal introduces a small, steady leak path the EVAP monitor can detect.
Common cause
Parts:purge valve
5
EVAP vent valve failure
Medium severity
A vent valve that doesn't seal fully during the monitor test produces a small-leak result.
Common cause
Parts:EVAP vent valve
6
Cracked charcoal canister
Medium severity
A hairline crack in the canister housing is a common source of a slow, small EVAP leak.
Common cause
Parts:charcoal canister

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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