P0442 on a 2015 GMC Canyon

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 2015 GMC Canyon

Ranked from 318 NHTSA owner complaints filed for this vehicle.

Sort by:

1
EVAP monitor/gas cap seal fault (false 'tighten cap' warning)
Medium severity
One owner replaced the fuel cap three times and still got the warning/check-engine light, pointing to the EVAP filler-neck seal or pressure sensor rather than the cap itself.
Reported in 1 NHTSA complaint
Parts:fuel cap
2
Fuel tank / line connection leak at the pump module
High severity
One owner traced a fuel odor and visible leak to the fuel feed/return line connections atop the in-tank pump, which can also compromise tank-side EVAP sealing.
Reported in 1 NHTSA complaint
3
Loose or worn gas cap
Low severity
The single most common small-leak trigger; the cap should click 3+ times when tightened and its gasket should be intact.
Common cause
Parts:fuel cap
4
Cracked or disconnected EVAP hose/line
Medium severity
Age-hardened rubber lines crack and leak vapor pressure, especially near the tank or canister.
Common cause
5
Purge valve stuck open
Medium severity
A leaking purge valve lets fresh air into the EVAP system during the leak-detection test, tripping a small-leak code.
Common cause
Parts:purge valve
6
Vent valve failure
Medium severity
A vent valve that won't seal prevents the system from holding vacuum/pressure during self-test.
Common cause
Parts:vent valve
7
Charcoal canister crack
Medium severity
A cracked canister housing is a common small, hard-to-find EVAP leak point.
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