P0442 on a 2018 Jeep Wrangler

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 Jeep Wrangler

Ranked from 1,793 NHTSA owner complaints filed for this vehicle.

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1
Fuel tank, filler neck, or EVAP line leak
High severity
Owners reported gasoline actively leaking/gurgling from the tank area or from above the tank, consistent with a leak in the tank, filler neck, or an EVAP vapor line.
Reported in 2 NHTSA complaints
Parts:fuel tank EVAP hose
2
EVAP canister flooded/saturated from a fuel tank overfill fault
Medium severity
A dealer explicitly determined that the fuel tank was 'not taking fuel properly' and had filled the EVAP canister with liquid fuel on one of these vehicles — a direct, documented EVAP-system failure mode.
Reported in 1 NHTSA complaint
Parts:charcoal canister
3
Restricted or faulty EVAP vent valve/fill-limiter
Medium severity
An owner could not fill the tank to its rated capacity, a classic symptom of a vent path that isn't venting air properly as the tank fills, pointing to the EVAP vent valve or fill-limiter vent.
Reported in 1 NHTSA complaint
Parts:vent valve
4
Loose, damaged, or missing gas cap
Low severity
The most common general cause of a small EVAP leak code; check/reseat or replace the cap and its seal first.
Common cause
Parts:gas cap
5
Purge valve (canister purge valve) stuck or malfunctioning
Medium severity
A purge valve that won't seal properly leaks the EVAP system to atmosphere and will fail a small-leak monitor test.
Common cause
Parts:purge valve
6
Cracked charcoal canister housing
Low severity
A crack in the canister itself provides a leak path that the small-leak monitor will detect.
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