P0455 on a 2016 Honda Civic

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 2016 Honda Civic

Ranked from 1,061 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Capless fuel filler flapper/seal failure
High severity
This generation's capless fuel filler is widely reported to backflow and spill fuel at refueling and fail to seal afterward — a large-leak-sized fault, not a missing cap.
Reported in 6 NHTSA complaints
Parts:fuel filler seal/flapper assembly
2
Rusted or corroded fuel tank / filler neck causing a seal leak
High severity
Several owners had the top of the fuel tank rust through at the pump sealing surface or filler neck, confirmed by dealer inspection after an emissions warning.
Reported in 3 NHTSA complaints
Parts:fuel tank filler neck
3
EVAP purge/vent valve or fuel tank pressure (FTP) sensor malfunction
Medium severity
One owner's dealer diagnosis was P2422 EVAP canister vent solenoid stuck closed with FTP sensor/canister malfunction.
Reported in 1 NHTSA complaint
Parts:EVAP purge valve canister vent valve fuel tank pressure sensor
4
Loose-fitting fuel filler assembly after repeated overfill events
Low severity
Repeated pump-shutoff/backflow events reported by owners can stress and loosen the filler neck seal over time.
Reported in 1 NHTSA complaint
5
Charcoal canister crack or stuck-open vent valve
Medium severity
A cracked canister or vent valve that won't close is a common large-leak source.
Common cause
Parts:charcoal canister EVAP vent valve
6
Cracked or disconnected EVAP hose/line
Medium severity
A fully split or disconnected line between canister, purge valve, and tank produces a large-leak reading.
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