P0455 on a 2015 Cadillac Srx

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 Cadillac Srx

Ranked from 442 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Failing EVAP purge valve (stuck open)
Medium severity
An owner reported the evaporative purge valve failing outright; for a large-leak code this usually means the valve is stuck open rather than just seeping.
Reported in 1 NHTSA complaint
Parts:EVAP purge valve
2
EVAP solenoid failure with continuous gas-cap light
Medium severity
An owner's EVAP solenoid failure, paired with a constant gas-cap warning, is consistent with a larger system leak rather than a marginal one.
Reported in 1 NHTSA complaint
Parts:EVAP solenoid
3
Missing, loose, or badly damaged gas cap
Low severity
An unsealed or missing gas cap is the most common cause of a large EVAP leak code.
Common cause
Parts:fuel cap
4
Cracked or split EVAP line/hose
Medium severity
A larger crack or a fully split section of EVAP tubing produces enough leak flow to fail the large-leak monitor.
Common cause
Parts:EVAP hose
5
Cracked charcoal canister
Medium severity
A cracked canister housing is a large enough leak path to set the large-leak threshold rather than the small-leak code.
Common cause
Parts:charcoal canister
6
Rusted or corroded fuel filler neck
Medium severity
Rust-through on the filler neck, common on SRXs that see road salt, creates an open leak path large enough to trigger this code.
Common cause
Parts:fuel filler neck

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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