P0442 on a 2017 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 2017 Jeep Wrangler

Ranked from 304 NHTSA owner complaints filed for this vehicle.

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1
Fuel tank vent/pressure control valve failure causing overfill and vapor leaks
High severity
Multiple owners had a diagnosed crack or inoperative fuel tank control/vent valve that let vapor escape and caused fuel to overflow at fill-up, and one reported a chronic filler-tube overflow at every fill — all consistent with a small/large EVAP leak.
Reported in 4 NHTSA complaints
Parts:fuel tank vent valve filler neck
2
Faulty or improperly sealing gas cap
Low severity
One owner replaced the gas cap twice for a recurring fuel-cap/check-engine light without full resolution, suggesting the cap was a contributing but not sole factor.
Reported in 1 NHTSA complaint
Parts:gas cap
3
Fuel sending unit/tank assembly defect
Medium severity
Owner cites an FCA recall campaign (16V849) for a defective fuel sending component on 2017 Jeeps not covered by their VIN, indicating a known tank-assembly manufacturing defect.
Reported in 1 NHTSA complaint
Parts:fuel level sending unit
4
Cracked or deteriorated EVAP hoses/lines
Medium severity
Age-hardened rubber lines crack and leak vapor slowly, a common general EVAP fault.
Common cause
Parts:evap hose
5
Purge valve failure (stuck open or leaking)
Medium severity
A leaking purge valve fails the system's leak-detection test even without a hole in the tank or lines.
Common cause
Parts:purge valve
6
Cracked charcoal canister
Medium severity
A split canister housing from age or vibration is a common slow-leak source.
Common cause
Parts:charcoal canister
7
Rusted or corroded fuel filler neck
Low severity
Corrosion at the filler neck seam breaks the EVAP seal in salt-belt climates.
Common cause
Parts: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.

Matching symptoms

Check Engine Light