P0455 on a 2016 Jeep Patriot
P0455 means the EVAP system failed a leak check badly enough that the computer sees a large leak or no pressure/vacuum change.
Not your vehicle? See general P0455 info.
Most common causes on the 2016 Jeep Patriot
Ranked from 455 NHTSA owner complaints filed for this vehicle.
- 1
Loose, damaged, or missing gas cap/seal
Medium severityA check-engine 'gas cap' notification persisted for one owner even with a new aftermarket cap, and a large leak most often traces back to the cap/filler-neck seal.
Reported in 1 NHTSA complaintParts:fuel cap - 2
EVAP purge/vent valve stuck open
Medium severityOne owner's leak code survived an emissions cleaner and new gas cap, pointing to a canister-side valve stuck open rather than the cap.
Reported in 1 NHTSA complaint - 3
Cracked or disconnected EVAP hose/line
Medium severityA larger split or a hose popped off a fitting produces enough leak flow to fail the large-leak threshold.
Common cause - 4
Cracked charcoal canister housing
Medium severityA split canister shell is a common source of a leak large enough to fail this monitor.
Common causeParts:EVAP charcoal canister - 5
Rusted or damaged filler neck
Low severityA perforated or heavily corroded filler neck is an obvious large leak path.
Common cause - 6
Faulty EVAP leak-detection (fuel tank pressure) sensor
Low severityA drifting FTP sensor can report a large 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. P0455 on your car still needs shop confirmation before any repair.
Common symptoms
- Check engine light
- Fuel smell
- Usually no performance issue
- Failed emissions readiness
What to check before replacing parts
Check the gas cap first
Look for: A loose, missing, or cross-threaded cap is by far the most common cause of a large EVAP leak code — if it doesn't click to full tightness or the seal is cracked, that's very likely the whole fault.
Inspect visible EVAP hoses
Look for: A large leak is often obvious: a hose disconnected at a fitting, split open, or chewed through (rodent damage is common) rather than a hairline crack.
Command the purge and vent valves with a scan tool
Look for: A valve that doesn't respond at all when commanded open/closed, or stays open when it should seal, prevents the system from holding pressure/vacuum and reads as a large leak.
Smoke-test the system
Look for: With a large leak, expect an obvious plume of smoke or a clearly audible hiss at the fault location — it should be easy to spot compared to a small-leak diagnosis.
Inspect the canister and filler neck
Look for: A cracked charcoal canister housing or a corroded/rusted-through filler neck (common on older vehicles) can leak enough to prevent the system from ever holding vacuum.
Rather have a pro handle it? Find a vetted local mechanic.