P0442 on a 2016 Jeep Patriot
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 2016 Jeep Patriot
Ranked from 455 NHTSA owner complaints filed for this vehicle.
- 1
EVAP purge/vent solenoid or canister fault (misdiagnosed as gas cap)
Medium severityOne owner's small-leak code persisted through an emissions cleaner and a new gas cap, pointing past the cap to a canister-side valve or the canister itself.
Reported in 1 NHTSA complaint - 2
Loose or damaged gas cap/seal
Medium severityA check-engine 'gas cap' notification persisted for one owner even after installing an aftermarket cap, consistent with a worn filler-neck seal rather than the cap itself.
Reported in 1 NHTSA complaintParts:fuel cap - 3
Cracked charcoal canister
Medium severityA cracked canister shell is a common small-leak source that typically requires a smoke test to isolate.
Common causeParts:EVAP charcoal canister - 4
Cracked or disconnected EVAP hose/line
Medium severityAge-hardened or damaged EVAP lines under the vehicle create a small vacuum leak the system's monitor detects.
Common cause - 5
Rusted or corroded filler neck
Low severityCorrosion around the filler neck seal area is a common source of a persistent small vapor leak on older vehicles.
Common cause - 6
Faulty EVAP leak-detection (fuel tank pressure) sensor
Low severityA drifting FTP sensor can report a leak during the self-test even when the system is actually sealed.
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.
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