P0455 on a 2019 Chevrolet Silverado 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 2019 Chevrolet Silverado 1500

Ranked from 1,035 NHTSA owner complaints filed for this vehicle.

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1
EVAP vent valve/solenoid circuit fault
Medium severity
One owner's scan tool logged a recurring P0499 (EVAP vent valve/solenoid circuit high) alongside the leak code; a vent valve stuck open (or unable to close) is a classic large-leak signature.
Reported in 1 NHTSA complaint
Parts:vent valve solenoid
2
Fuel pump control module (FPCM) fault blocking EVAP canister venting
Medium severity
One owner's CEL was traced to the fuel pump control module, which their shop stated was preventing the EVAP system from venting fuel vapors properly; GM has recalled related FPCM hardware on other model-year trucks.
Reported in 1 NHTSA complaint
Parts:fuel pump control module
3
Canister purge valve failure
Medium severity
One owner reports the purge ("purge pump") valve failing three separate times, alongside catalytic converter and check-engine issues; a purge valve stuck open lets unmetered air/vacuum into the system.
Reported in 1 NHTSA complaint
Parts:purge valve
4
Damaged/broken fuel filler cap hardware
Low severity
One owner found the spring-loaded fuel cap flap mechanism broken and falling into the filler neck, which would prevent the cap/flap from sealing properly.
Reported in 1 NHTSA complaint
Parts:fuel filler cap
5
Physical fuel tank breach/rupture
High severity
One owner's plastic fuel tank ruptured from road debris while towing, dumping fuel; a breach of this size at the tank is a textbook large-leak (P0455) event even though the direct cause is impact damage rather than wear.
Reported in 1 NHTSA complaint
Parts:fuel tank
6
Corroded or rusted fuel filler neck
Medium severity
Rust-through at the filler neck (common on trucks that see road salt) is a large, unmistakable opening in the vapor system.
Common cause
Parts:fuel filler neck
7
Disconnected or split EVAP hose/line
Medium severity
A fully detached or badly split hose between the tank, canister, and purge valve creates an opening large enough to fail the large-leak threshold outright.
Common cause
Parts:EVAP hose

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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