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P0455

P0455 on a 2017 Jeep Grand Cherokee

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 2017 Jeep Grand Cherokee

Ranked from 361 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Capless fuel filler neck flap stuck open or torn

    Medium severity

    Multiple owners describe the capless filler system on this vehicle failing to seal during fill-up (won't take fuel without holding/inverting the nozzle, spills), which can be large enough to fail the large-leak test.

    Reported in 3 NHTSA complaints
    Parts:fuel filler neck
  2. 2

    EVAP purge valve or purge hose failure

    Medium severity

    One owner's repair history on this vehicle explicitly lists the EVAP purge hose and EVAP purge solenoid both being replaced, a direct hit for this code family.

    Reported in 1 NHTSA complaint
    Parts:purge valveEVAP hose
  3. 3

    Missing, loose, or cross-threaded gas cap

    Low severity

    The most common cause of a large-leak code; the system can't hold vacuum/pressure without a properly seated cap.

    Common cause
    Parts:fuel cap
  4. 4

    Disconnected or split EVAP hose

    Medium severity

    A hose knocked loose during service or torn through age creates a wide-open path to atmosphere.

    Common cause
    Parts:EVAP hose
  5. 5

    EVAP purge or vent valve stuck open

    Medium severity

    A valve stuck fully open prevents the system from ever sealing during the leak test.

    Common cause
    Parts:purge valvevent valve
  6. 6

    Cracked charcoal canister

    Medium severity

    A significant crack in the canister housing is large enough to fail the gross-leak threshold.

    Common cause
    Parts:charcoal canister

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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