P0442 on a 2017 Toyota Tacoma

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 Toyota Tacoma

Ranked from 237 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel filler door damaged/won't close, breaking the cap seal
Low severity
One owner reports the fuel filler door broke and would no longer close after a fill-up, which prevents the gas cap area from sealing and produces a small EVAP leak.
Reported in 1 NHTSA complaint
Parts:fuel filler door gas cap
2
EVAP leak-detection pump / charcoal canister assembly beginning to fail
Medium severity
An owner reports the leak detection pump sub-assembly at the charcoal canister pumping loudly for minutes at a time after long idle periods, a sign the LDP is struggling to build/hold vacuum for the EVAP self-test.
Reported in 1 NHTSA complaint
Parts:leak detection pump charcoal canister
3
Loose or worn gas cap seal
Low severity
A cap that seats but has a hardened/cracked seal is the single most common cause of a small EVAP leak code.
Common cause
Parts:gas cap
4
Small crack or pinhole in an EVAP hose or line
Medium severity
Age-hardened rubber/plastic EVAP lines near the engine or exhaust develop small cracks over time.
Common cause
5
Purge valve leaking slightly (not fully seating)
Medium severity
A purge solenoid that doesn't fully close allows a small, steady leak detected during the fine-leak EVAP test.
Common cause
Parts:purge valve
6
Vent valve seal degraded
Medium severity
A worn vent valve seal allows a small amount of leakage past the valve during the sealed portion of the EVAP test.
Common cause
Parts:vent valve

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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