P0455 on a 2022 Ram 1500 Crew Cab Trx

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 2022 Ram 1500 Crew Cab Trx

Ranked from 588 NHTSA owner complaints filed for this vehicle.

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1
EVAP tank vent/fill valve fault
High severity
An owner found the valve at the base of the tank (part of the EVAP system) blocking fill-ups, with the dealer calling it a common issue on these trucks needing a new fuel tank — this is a direct large-leak source.
Reported in 1 NHTSA complaint
Parts:EVAP vent valve
2
Cracked, loose, or disconnected EVAP line
Medium severity
An owner's truck showed a check-engine light with a technician-confirmed emissions system leak alongside a failing fuel pump, consistent with a disconnected or cracked EVAP hose producing a large leak.
Reported in 1 NHTSA complaint
Parts:EVAP hose
3
Loose or missing gas cap
High severity
The most common cause of a large EVAP leak code; a cap left loose or off after fueling won't hold system pressure at all.
Common cause
Parts:gas cap
4
Purge valve stuck open
Medium severity
A purge valve stuck fully open holds the EVAP system open to intake vacuum continuously, easily failing the large-leak test.
Common cause
Parts:purge valve
5
Charcoal canister crack
Medium severity
A larger crack or a canister housing failure produces a leak big enough to fail the large-leak monitor.
Common cause
Parts:charcoal canister
6
Rusted or damaged filler neck
Low severity
A significantly corroded or dented filler neck can no longer seal against the cap/door at all.
Common cause
Parts:fuel filler neck

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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.

Matching symptoms

Check Engine Light