P0442 on a 2024 Mazda Cx 90 Phev
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 2024 Mazda Cx 90 Phev
Ranked from 407 NHTSA owner complaints filed for this vehicle.
- 1
EVAP/fuel-vapor system malfunction with raw fuel-vapor odor (reported fuel tank pressurization failures on this model)
High severityMultiple owners describe a fuel tank pressurization system failure and a persistent raw gasoline vapor smell, consistent with a purge/vent circuit that won't seal.
Reported in 2 NHTSA complaints - 2
Fuel filler door/gas cap access fault preventing a proper seal
Low severityA gas door reported stuck closed can leave the cap unseated or force owners to skip capping it correctly.
Reported in 1 NHTSA complaint - 3
Loose, damaged, or missing gas cap
Low severityStandard check for any small EVAP leak code.
Common causeParts:gas cap - 4
Cracked or disconnected EVAP hose/line
Medium severityBrittle plastic fittings under the hood or near the tank are a frequent small-leak source.
Common cause - 5
Charcoal (carbon) canister crack
Medium severityA cracked canister body won't hold vapor pressure during the EVAP self-test.
Common causeParts:charcoal canister - 6
Fuel tank pressure (FTP) sensor fault
Low severityA drifting FTP sensor can falsely report a leak; confirm with a smoke test first.
Common cause - 7
Rusted or damaged fuel filler neck
Medium severityCorrosion at the neck-to-tank joint is a known small-leak path.
Common cause
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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.