P0442 on a 2011 Toyota Sienna

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 Toyota Sienna

Ranked from 610 NHTSA owner complaints filed for this vehicle.

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1
EVAP pressure switching/vent valve stuck
Medium severity
A dealer diagnosed this Sienna's fuel emission (EVAP) pressure switch valve as stuck in the off position (P2440) — the same purge/vent hardware that governs P0442/P0455.
Reported in 1 NHTSA complaint
Parts:evap purge valve vent switching valve
2
Loose or faulty gas cap
Low severity
An owner was told to replace the gas cap after the VSC/check-engine lights came on for this same complaint pattern; check cap seal and threads first.
Reported in 1 NHTSA complaint
Parts:gas cap
3
Loose, damaged, or missing gas cap
Low severity
A worn, cracked, or not-fully-seated gas cap seal is the single most common trigger for a small EVAP leak (P0442); confirm it clicks fully closed and the seal isn't cracked.
Common cause
Parts:gas cap
4
Cracked or disconnected EVAP hose/line
Medium severity
Rubber and plastic EVAP lines running between the tank, canister, purge valve, and intake harden and crack with age, or get knocked loose during other service work.
Common cause
Parts:evap hose evap line
5
Purge valve stuck open or leaking
Medium severity
A purge solenoid that doesn't seal lets outside air bleed into the system during the leak test, mimicking a real leak; a smoke test with the valve commanded closed will confirm it.
Common cause
Parts:purge valve
6
Canister vent (CVS) solenoid stuck open or clogged
Medium severity
The vent valve must seal the system for the PCM to pressurize/vacuum-test it; a stuck-open, corroded, or debris/ice-clogged vent valve causes a leak to be reported every time.
Common cause
Parts:vent valve canister vent solenoid
7
Cracked charcoal canister
Medium severity
The plastic canister housing can crack from age, road debris, or corrosion, producing a leak that only shows during the EVAP monitor.
Common cause
Parts:charcoal canister
8
Rusted or perforated fuel tank / filler neck
Medium severity
Road salt and age corrode steel filler necks and tank seams, opening a pinhole that leaks vapor (and eventually fuel).
Common cause
Parts:fuel tank filler neck
9
Faulty fuel tank pressure (FTP) sensor
Low severity
A drifting or failed FTP sensor can report a false leak even when the EVAP system is physically sealed; compare live sensor data against a known-good reading.
Common cause
Parts:fuel tank pressure sensor
10
EVAP leak detection pump/module failure
Low severity
On systems that use a dedicated leak-detection pump (or engine-off natural vacuum test) instead of engine vacuum, a weak or failed pump/module can't build the required test pressure and sets the code.
Common cause
Parts:evap leak detection pump

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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