P0455 on a 2015 Nissan Sentra

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 Nissan Sentra

Ranked from 348 NHTSA owner complaints filed for this vehicle.

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1
Cracked or leaking fuel tank sending unit / sender seal
High severity
Owner reported a mechanic-confirmed 'cracked, leaking sending unit at connector, plastic mold' on the tank top, the same failure Nissan recalled on the related 2015 Altima/Maxima but not the Sentra; a leak at this in-tank seal opens a large path in the sealed EVAP system.
Reported in 1 NHTSA complaint
Parts:fuel level sending unit sending unit seal
2
Persistent EVAP leak not resolved by gas cap replacement
Medium severity
Owner reported code recurring repeatedly even after replacing the gas cap, pointing to a leak point elsewhere in the EVAP system (line, valve, or canister) rather than the cap itself.
Reported in 1 NHTSA complaint
3
Loose, worn, or improperly seated gas cap
Low severity
Most common cause of a large EVAP leak code; check for a properly clicking, undamaged cap and gasket.
Common cause
Parts:gas cap
4
Cracked or perished EVAP purge/vent hose
Medium severity
Rubber/plastic EVAP lines harden and crack with age and heat cycling, opening a large vapor leak path.
Common cause
Parts:EVAP hose/line
5
Failed EVAP purge valve stuck open
Medium severity
A purge valve stuck open lets fresh air continuously into the fuel tank vapor system, which the ECU reads as a large leak.
Common cause
Parts:purge valve
6
Failed EVAP canister vent valve stuck open
Medium severity
A vent valve that won't seal prevents the EVAP system from holding vacuum/pressure during the monitor test.
Common cause
Parts:vent valve
7
Cracked or saturated charcoal canister
Medium severity
A cracked canister housing or waterlogged charcoal media breaks the seal of the EVAP system.
Common cause
Parts:charcoal canister
8
Corroded or damaged fuel filler neck
Medium severity
Rust-through or damage on the filler neck itself creates a large, easily detected EVAP leak.
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