P0455 on a 2015 Chevrolet Suburban 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 2015 Chevrolet Suburban 1500

Ranked from 428 NHTSA owner complaints filed for this vehicle.

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1
Chafed/leaking plastic fuel feed line & tank vent hardware (GM TSB 17-NA-304)
High severity
By far the dominant complaint for this vehicle: the fuel feed line and fittings at the top of the tank rub through and leak raw fuel, a breach large enough to fail the EVAP leak monitor outright and produce a strong gasoline smell.
Reported in 19 NHTSA complaints
Parts:fuel feed line fuel tank vent line fuel line clips/retainer
2
Intermittent high-pressure fuel pump leak (GM bulletin 14858/SB-10057680)
Medium severity
A separate GM service bulletin covers an intermittent leak at the high-pressure fuel pump that triggers the check-engine light on this generation.
Reported in 1 NHTSA complaint
Parts:fuel pump
3
Loose, worn, or missing gas cap
Low severity
The most common general cause of a large EVAP leak code; check the cap seal and threads first.
Common cause
Parts:fuel filler cap
4
Cracked or split EVAP canister
Medium severity
A cracked canister housing is a large enough breach to fail the monitor outright rather than intermittently.
Common cause
Parts:EVAP charcoal canister
5
Disconnected or split EVAP vapor line
Medium severity
A hose popped off a fitting or split open is one of the most common large-leak findings on a smoke test.
Common cause
Parts:EVAP vapor hose
6
Rusted or corroded fuel filler neck / tank
Medium severity
Road-salt corrosion perforates the filler neck or tank seams over time, producing a large, easily detected leak.
Common cause
Parts:fuel filler neck fuel tank

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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