P0455 on Jeep: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Gross Leak)
2 Jeep models · 3 documented issues · $20-$350 repair
P0455 on Jeep by model: symptoms, diagnosis and fix
The Jeep Grand Cherokee uses a Natural Vacuum Leak Detection (NVLD) approach for its EVAP system, implemented through the Evaporative System Integrity Module (ESIM) — commonly called the leak detection pump. The ESIM is a standalone unit (typically mounted on the charcoal canister near the rear driver-side wheel well) that seals the fresh-air vent and uses natural temperature-induced pressure changes to verify the fuel-vapor system holds vacuum. The internal seal/diaphragm and check mechanism in the ESIM are a well-documented common failure point on Chrysler/Jeep platforms. When the unit fails, the PCM cannot complete its EVAP self-test and falsely reports an EVAP leak, illuminating the check engine light even though no actual leak exists. Because the same codes are thrown by a loose or worn gas cap, the failure is frequently misdiagnosed: owners (and even shops) replace the gas cap first, the light returns, and the actual ESIM/leak-detection-pump fault is missed. A simple field test is to remove the ESIM and shake it — a rattle indicates the internal valve has come loose and the unit needs replacement. Note that a split EVAP purge-valve hose (TSB 25-002-15 Rev. A, 2015 3.6L/5.7L units built Nov 16, 2014 to Jan 17, 2015) and a disconnected fuel vapor hose in the left rear wheel well (TSB 18-035-20, 2020 3.6L units built Nov 4, 2019 to Mar 9, 2020) produce the same codes, so the hoses should be inspected before condemning the ESIM. This is an emissions-only fault: it does not harm the engine or transmission but will fail a state emissions/smog test.
Common Symptoms
- Check engine light on (often intermittent, may clear and return)
- OBD-II scan shows P0456 (small EVAP leak), P0455 (large EVAP leak), or P0457 (loose fuel cap / large leak)
- "Check Fuel Cap" / gas cap warning message
- Fuel/gasoline odor near the vehicle in some cases
- Failed state emissions or smog test
- Light returns shortly after a gas cap replacement (sign of misdiagnosis)
- Occasional slightly extended cranking
- ESIM rattles when removed and shaken (failed internal valve)
How to Fix
Diagnose before replacing parts. (1) Inspect/re-tighten or replace the gas cap and confirm it clicks and seals — rule out the cheapest cause first. (2) Visually inspect the thin plastic EVAP purge-valve hose on top of the engine for cracks/splits (especially at connection points) per TSB 25-002-15 Rev. A, and on 2020 3.6L units check the fuel vapor hose quick connector in the left rear wheel well per TSB 18-035-20; replace or reconnect as needed — this alone fixes many cases. (3) Locate the ESIM/leak detection pump (on the charcoal canister near the rear driver-side wheel well); remove and shake it — if it rattles, the internal valve has failed. On 2013-2016 models, FCA requires the EELD/smoke test and confirmation that PCM flash updates have been performed before the ESIM or canister is replaced. Replacement is a straightforward DIY: a new ESIM (OEM, or aftermarket such as Dorman 310-219) installs in place of the old one. After replacement, clear the codes and complete a few drive/fill cycles to confirm the EVAP monitor passes and the light stays off. If codes persist after ESIM and hose service, smoke-test the EVAP system to find a remaining leak (canister, lines, or fuel-tank-side seals).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar purge hose for the 3.6L ERB bulletin branchOEMMopar 68189075AE
A repair after a split hose is confirmed on an in-window 2015 WK 3.6L ERB Fitment/availability: 68189075AE supersedes AC/AD and is cataloged for 2014-2015 Grand Cherokee 3.6L.
- Genuine Mopar purge hose for the 5.7L EZH bulletin branchOEMMopar 68189065AD
A repair after a split hose is confirmed on an in-window 2015 WK 5.7L EZH Fitment/availability: 68189065AD supersedes AB/AC and is cataloged for 2014-2015 Grand Cherokee 5.7L.
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Owner tips & cautions
- WarningP0455/P0456 does not identify an ESIM, gas cap, canister, or hose by itself. Match the build window and inspect or smoke-test the system before buying a part.
- TipUse the VIN and engine sales code to distinguish the 3.6L and 5.7L purge hoses before ordering.
Sources for this issue (3)
WK2 Grand Cherokees use a capless (Easy Fuel) filler neck with a spring-loaded flapper door and an internal one-way check valve. Over time the flapper mechanism sticks or fails to seal, and the check valve at the tank inlet can hang up, causing the fuel pump nozzle to click off repeatedly and refuse to fill the tank — the classic 'won't take gas' complaint, often worse with modern ORVR pump nozzles. FCA revised the filler-neck part number multiple times, indicating a recognized design weakness. Beyond the fueling nuisance, a poorly sealing filler can contribute to EVAP (P0455/P0456) complaints.
Common Symptoms
- Fuel pump nozzle clicks off after a few seconds
- Tank very slow to fill or won't accept fuel
- Fuel splashback at the filler
- Broken or stuck flapper door in the filler
- Occasional EVAP check-engine light (P0455/P0456)
- Must trickle-fill to top off the tank
How to Fix
Inspect the capless filler neck flapper and internal check valve; clean debris and verify the flapper closes/seals. If it sticks or the nozzle keeps clicking off, replace the capless fuel filler neck with the latest revised part. As a temporary field workaround owners report inserting the nozzle more slowly (or gently holding the flapper open) — but the durable fix is filler-neck replacement. Rule out a plugged EVAP/vent restriction if fill problems persist after replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar fuel tank filler tube for ERC/EZH bulletin branchOEMMopar 68377769AE
The TSB's engine-code and year branch controls; verify VIN/current supersession.
- Genuine Mopar fuel tank filler tube for ESG/ESD bulletin branchOEMMopar 68250911AN
The live listing is genuine/new; use the TSB and VIN/engine sales code rather than its broader compatibility table.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningDo not order by the symptom alone. FCA requires the other hard-to-fill diagnostics first, and the correct tube changes with engine sales code and model year.
- TipHave the seller or installer verify the VIN, engine sales code, and current Mopar supersession before the order is placed.
Sources for this issue (1)
JK owners report check-engine lights for evaporative-system leaks (P0455, P0456) that a new gas cap did not fix. Owners report the leak at the small white leak-detection module and its seal on the black charcoal canister, the canister's fresh-air filter or check valve, or a plastic vapor line on top of the tank. The fault affects emissions testing, not how the Jeep drives. Applies to: 2007-2018 Jeep Wrangler and Wrangler Unlimited (JK), all engines.
Common Symptoms
- Check-engine light with small EVAP leak code P0456
- Check-engine light with code P0455 after mud driving
- EVAP code comes back a few hundred miles after clearing
- Gas cap warning appears on and off
How to Fix
First make sure the gas cap clicks shut and its seal is not cracked. If the code returns, owners report a smoke test finds the leak quickly; common finds are the leak-detection module or its seal on the canister. Clear the code after the repair and allow a few drive cycles for the emissions monitor to rerun.
Sources for this issue (3)
P0455 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0455 mean on a Jeep?
P0455 stands for "Evaporative Emission Control System Leak Detected (Gross Leak)." This code means your car's evaporative emission (EVAP) system has detected a large (gross) leak, so fuel vapors that should be sealed inside the fuel and vapor system are escaping into the atmosphere. The EVAP system captures gasoline vapors from the tank and routes them to the engine to be burned instead of polluting the air, and the computer periodically pressure- or vacuum-tests this sealed system. A gross leak almost always points to something obvious and easy, like a loose, missing, or bad gas cap, rather than a deep mechanical failure. It rarely affects how the car drives, but it should be fixed to pass emissions and stop wasting fuel vapor. On Jeep it is documented across 2 models: Grand Cherokee, Wrangler.
What are the most common causes of P0455?
The most common causes of P0455 are: Loose, missing, or improperly tightened gas cap, Worn, cracked, or failed gas cap seal, Cracked or disconnected EVAP/vapor hose, Damaged or missing fuel filler neck seal, Faulty EVAP purge valve stuck open, Failed EVAP vent valve, Cracked or damaged charcoal canister. The specific cause varies by vehicle.
How much does it cost to fix P0455 on a Jeep?
Published repair estimates on Jeep range from $20 to $350 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.