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P0455

P0455 on a 2021 Honda Cr V

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 2021 Honda Cr V

Ranked from 311 NHTSA owner complaints filed for this vehicle.

Sort by:
  1. 1

    Failing high-pressure fuel pump seal

    Medium severity

    Several owners of this vehicle had confirmed fuel pump failures (a known Honda fuel-pump recall pattern) that can leak enough fuel vapor to register as a large EVAP leak.

    Reported in 4 NHTSA complaints
    Parts:fuel pump
  2. 2

    Fuel vapor leak presenting as strong fuel odor from cabin vents

    Medium severity

    One owner of this exact vehicle reported a strong, persistent fuel smell from the vents at highway speed, consistent with a leak large enough to fail the big-leak EVAP monitor.

    Reported in 1 NHTSA complaint
  3. 3

    Loose or missing gas cap

    Low severity

    The single most common large-leak cause across all vehicles; recheck for a proper click and inspect the seal.

    Common cause
    Parts:fuel cap
  4. 4

    Purge valve stuck open

    Medium severity

    A purge valve stuck open bleeds down system pressure rapidly, presenting as a large leak.

    Common cause
    Parts:purge valve
  5. 5

    Canister vent valve failure

    Medium severity

    A vent valve that fails to close allows continuous atmospheric venting, a common large-leak trigger.

    Common cause
    Parts:vent valve
  6. 6

    Charcoal canister crack

    Medium severity

    A significant crack in the canister housing can leak enough fuel vapor to fail the large-leak test.

    Common cause
    Parts:charcoal canister
  7. 7

    Cracked or disconnected EVAP line

    Medium severity

    A larger split or a hose popped off a fitting produces an obvious large leak; smoke test to pinpoint it.

    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

1

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.

2

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.

3

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.

4

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.

5

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