P0455 on a 2016 Ford Focus Bev

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 Ford Focus Bev

Ranked from 1,137 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Canister purge valve (CPV) failure/stuck (known Ford recall issue, code P1450)
High severity
The dominant reported cause across this vehicle population: a failed/stuck fuel tank/canister purge valve, frequently paired with DTC P1450, causes stalling on refueling and is large enough in several reports to trip a large-leak EVAP code; covered by Ford recall campaigns (e.g., 24N07) for the CPV.
Reported in 20 NHTSA complaints
Parts:purge valve
2
Collapsed or dented fuel tank (secondary to a stuck-closed CPV)
Medium severity
A purge valve stuck closed builds excess vacuum in the tank while driving, collapsing/denting it; the deformed tank/seal area can open a large EVAP leak path.
Reported in 2 NHTSA complaints
Parts:fuel tank
3
Missing, unseated, or badly torn gas cap
High severity
A cap left off, cross-threaded, or with a torn seal is the most common large-leak cause and is easily ruled out first.
Common cause
Parts:gas cap
4
Large split or disconnected EVAP hose/line
Medium severity
A fully detached or split purge/vent line is large enough to fail the large-leak monitor; trace the full EVAP hose run.
Common cause
5
Cracked charcoal canister or housing
Medium severity
A significant crack creates a large leak path; inspect for physical damage and fuel odor.
Common cause
Parts:charcoal canister
6
Damaged or disconnected fuel tank pressure (FTP) sensor/seal
Low severity
A leaking or unplugged FTP sensor cannot register the expected vacuum/pressure buildup, which reads as a large leak.
Common cause
Parts:fuel tank pressure sensor

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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