P0455 on a 2022 Ram 1500 Classic Regular 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 Regular Cab

Ranked from 588 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank vent/isolation valve failure preventing normal fill and sealing
High severity
One owner's dealer traced a refueling/EVAP fault to the valve at the base of the tank, with a broken fuel-tank nipple found on a spare unit — a large enough fault to fail the P0455 threshold, and described as common on these trucks.
Reported in 1 NHTSA complaint
Parts:fuel tank vent valve fuel tank
2
Small emissions/EVAP leak that has progressed to a larger fault
Medium severity
One owner's scan already showed a small emissions-system leak alongside a failing fuel pump, and unaddressed small leaks commonly worsen into large-leak faults.
Reported in 1 NHTSA complaint
3
Loose, missing, or badly worn gas cap
Low severity
The classic large-leak trigger and the first thing to check before deeper EVAP diagnosis.
Common cause
Parts:fuel cap
4
Cracked or disconnected EVAP hose/line
Medium severity
A significantly cracked or detached vapor line is large enough to fail the large-leak threshold.
Common cause
Parts:EVAP hose
5
EVAP vent valve stuck open
Medium severity
A vent valve that won't close prevents the system from holding vacuum during the test.
Common cause
Parts:vent valve
6
Cracked charcoal canister housing
Low severity
A significant canister crack is large enough to trip the large-leak threshold.
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