P0455 on a 2016 Ram 1500

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 Ram 1500

Ranked from 1,508 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Fuel tank strap corrosion causing tank to sag and stress/crack EVAP lines
High severity
Multiple owners report the front fuel tank strap rusting through and the tank sagging or dropping, which can stretch, kink, or crack the EVAP lines and fittings routed near the tank -- consistent with a large leak.
Reported in 6 NHTSA complaints
Parts:fuel tank strap
2
Restricted or corroded fuel filler neck
Medium severity
Owners describe the fill nozzle sticking or cutting off early, symptoms consistent with filler-neck or vent-path corrosion/restriction that can also open a large leak path.
Reported in 2 NHTSA complaints
Parts:fuel filler neck
3
Loose, worn, or missing gas cap
Low severity
This remains the single most common trigger for a large-leak EVAP code and should be the first thing checked.
Common cause
Parts:gas cap
4
Cracked or disconnected EVAP hose/line
Medium severity
A fully split or detached hose produces a large, continuous leak that a smoke test finds quickly.
Common cause
5
EVAP vent/canister valve failure
Medium severity
A vent valve stuck open leaves the system open to atmosphere for the whole monitor cycle, a classic large-leak cause.
Common cause
Parts:EVAP vent valve
6
Cracked charcoal canister
Medium severity
A cracked canister housing vents vapor directly to atmosphere and fails the leak test outright.
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