P0455 on a 2022 Ram 1500 Classic Crew Cab

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 Classic Crew Cab

Ranked from 588 NHTSA owner complaints filed for this vehicle.

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1
Faulty fuel tank/filler EVAP valve or broken filler-neck fitting
Medium severity
This truck's owner reported the EVAP valve at the base of the tank blocking refueling, with a broken fuel nipple found inside a replacement tank -- a large enough opening to set a P0455 gross-leak code, and described as a common issue on these Rams.
Reported in 1 NHTSA complaint
Parts:fuel tank EVAP vent valve
2
Emissions system leak reported alongside fuel-delivery fault
Low severity
Another owner's check-engine light was tied by the shop to an emissions system leak, consistent with a large EVAP leak pattern on this vehicle.
Reported in 1 NHTSA complaint
3
Loose or missing gas cap
Low severity
A cap left loose or off entirely is large enough to fail the EVAP monitor outright and is the first thing to rule out.
Common cause
Parts:fuel filler cap
4
Cracked or disconnected EVAP hose
Medium severity
A fully split or popped-off EVAP line creates an opening large enough for the gross-leak test to fail.
Common cause
5
Purge or vent valve stuck open
Medium severity
A valve that fails open holds the EVAP system at atmospheric pressure, which the monitor reads as a large leak.
Common cause
Parts:purge valve vent valve
6
Rusted-through or corroded filler neck
Medium severity
On trucks that see road salt or moisture, the metal filler neck can rust through, opening a large EVAP leak path.
Common cause
Parts:fuel filler neck
7
Cracked charcoal canister housing
Low severity
A significant crack in the canister body is large enough to fail the gross-leak portion of the EVAP monitor.
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. 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