P0455 on a 2019 Chevrolet Silverado Ld 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 Ld 1500

Ranked from 822 NHTSA owner complaints filed for this vehicle.

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1
Damaged or broken fuel filler cap/cap spring
High severity
An owner found the spring-loaded fuel cap mechanism broken and fallen into the filler area, preventing any seal — a classic large-leak trigger.
Reported in 1 NHTSA complaint
Parts:fuel filler cap
2
Fuel tank rupture or large fuel leak
High severity
One owner had the plastic fuel tank rupture from road debris while towing, dumping 20-25 gallons — a gross leak large enough to set P0455.
Reported in 1 NHTSA complaint
Parts:fuel tank
3
EVAP vent valve stuck closed/open (P0499)
High severity
An owner reports a recurring P0499 vent valve code, which on a large-enough fault also triggers the gross-leak monitor.
Reported in 1 NHTSA complaint
Parts:EVAP vent valve
4
Purge valve/pump failure
Medium severity
An owner's EVAP purge pump/valve failed three times, a direct and recurring hardware cause of EVAP leak codes.
Reported in 1 NHTSA complaint
Parts:EVAP purge valve
5
Fuel pump control module fault disrupting EVAP venting
Medium severity
An owner's EVAP circuit code was traced by the dealer to the fuel pump control module, which on this platform also affects the EVAP system's ability to vent properly.
Reported in 1 NHTSA complaint
Parts:fuel pump control module
6
Cracked or disconnected EVAP hose/line
Medium severity
A fully detached or split EVAP line is large enough to fail the gross-leak monitor.
Common cause
Parts:EVAP hose
7
Charcoal canister crack
Low severity
A significantly cracked canister housing can leak enough to trigger the gross-leak 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