P0442 on a 2011 Hyundai Sonata

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 2011 Hyundai Sonata

Ranked from 3,371 NHTSA owner complaints filed for this vehicle.

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1
EVAP purge or vent control valve failure
Medium severity
One complaint reports an explicit P0449 EVAP vent control valve code with the classic symptom of being unable to pump gas normally, and another describes gas spitting back / needing to fill slowly, both consistent with a stuck or malfunctioning purge/vent valve.
Reported in 2 NHTSA complaints
Parts:EVAP purge valve EVAP vent valve
2
Fuel tank pressure (FTP) sensor fault
Medium severity
One complaint reports a P0451 fuel-tank-pressure-sensor code with a fuel-delivery-like symptom; a faulty FTP sensor is part of the same EVAP monitoring circuit and can cause the system to falsely register a leak.
Reported in 1 NHTSA complaint
Parts:fuel tank pressure sensor
3
Loose, missing, or worn gas cap
Low severity
The single most common EVAP small-leak cause; check that the cap clicks fully and inspect the rubber seal.
Common cause
Parts:gas cap
4
Cracked or deteriorated EVAP hose or line
Medium severity
Age-hardened rubber lines between tank, canister, and purge valve can crack and leak vapor; smoke-test to pinpoint.
Common cause
5
Charcoal canister crack
Medium severity
A cracked canister housing leaks vapor past its normal seal; inspect for physical damage or fuel odor at the canister.
Common cause
Parts:charcoal canister
6
Rusted or damaged filler neck
Medium severity
Corrosion or physical damage near the gas cap seal creates a vapor leak path.
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.

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Matching symptoms

Check Engine Light