P0455 on Jeep: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Gross Leak)
2 Jeep models · 3 documented issues · $20-$450 repair
P0455 on Jeep by model: symptoms, diagnosis and fix
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)
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 the EVAP purge-valve hose on top of the engine also becomes brittle and cracks (covered by Jeep TSBs #25-002-15 REV-B and #18-035-20), producing the same codes, so the hose 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-B; replace if brittle/cracked — 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 and the module must be 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.
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
- 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 (2)
The JK-generation Jeep Wrangler uses Chrysler's Natural Vacuum Leak Detection (NVLD) approach for its evaporative emissions (EVAP) system, implemented through a leak detection device commonly called the ESIM (Evaporative System Integrity Module) or leak detection pump (LDP). Rather than an active vacuum pump, this module monitors natural temperature-induced pressure/vacuum changes in the fuel/EVAP system to confirm the system is sealed. The ESIM is a known, high-frequency failure point: its internal diaphragm/seal hardens or cracks (or the housing cracks), causing the ECM to falsely detect an EVAP leak even when the system is actually sealed. The result is a check-engine light and one of several EVAP leak codes. Because the very first thing the code points the owner toward is the fuel cap, this failure is routinely misdiagnosed: owners (and shops) replace the gas cap one or more times, the light returns, and the actual culprit is the cheap ESIM/leak-detection module bolted to the charcoal canister. The module is a small white rectangular unit that twists/mounts onto the EVAP charcoal canister, located beneath the vehicle near the fuel tank / just ahead of the rear axle (driver side on most JKs). It is non-safety, non-drivability affecting, but it will cause a persistent CEL and an emissions/smog-test failure. This affects the 3.8L V6 (2007-2011) and 3.6L Pentastar (2012-2018) JK Wranglers, including 2-door and Unlimited 4-door.
Common Symptoms
- Check-engine light (MIL) illuminated
- "GASCAP" / loose-fuel-cap warning message in the instrument cluster even when the cap is tight
- P0455, P0456, and/or P0457 stored as the only codes
- Check-engine light returns shortly after replacing or re-tightening the gas cap
- Occasional faint fuel-vapor odor near the rear of the vehicle
- Fails emissions / smog inspection (EVAP monitor not ready or DTC present)
- No noticeable change in engine performance, power, or fuel economy
How to Fix
Diagnose in order of cost. (1) First, confirm the gas cap clicks shut and is not cracked; if the cap is worn, replace with an OEM Mopar cap (P0457 / "GASCAP" message especially). A cap is the cheapest fix (under $30). (2) If the light returns after a known-good cap, perform a smoke test of the EVAP system to find any cracked vapor hose, leaking purge valve, or split canister before condemning the module. (3) If no external leak is found and codes persist (classic for P0456 small-leak and P0455 large-leak with no physical leak present), replace the ESIM / leak detection pump on the charcoal canister. The module is widely available (e.g., Standard Motor Products LDP14 and Mopar equivalents) and the replacement is a DIY-friendly job — typically under 30 minutes, no special tools, by twisting the module off the canister and installing the new one. Always install the new O-ring/seal supplied with the module; a poor seal will recreate the leak code. After replacement, clear the codes and complete a drive cycle so the EVAP monitor can re-run and confirm the repair. Note: if the failure is actually the charcoal canister itself (cracked) rather than just the module, the repair is more involved and more expensive.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Dorman 310-215 Evaporative System Integrity ModuleOEMDorman 310-215
Replace a test-confirmed failed ESIM after the cap and external EVAP system pass inspection/smoke testing Fitment/availability: Specific-fit ESIM cross for 2007-2018 Jeep applications and OE 4861962AA-AD/4891685AA-AB; confirm the Wrangle…
- Genuine Mopar 52030387AB non-locking tethered fuel capOEMMopar 52030387AB
Replace a cracked, hardened or non-sealing cap as the lowest-cost confirmed leak path Fitment/availability: 2007-2018 Wrangler JK gasoline branch within this issue; the product also fits 2003-2006 TJ.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (7)
- Jeep JK evap error fixes found — Jeep Wrangler Forum (P0455/P0456/P0457 + GASCAP, ESIM on canister, DIY fix)forum
- P0456 Code, Small Evap Leak FIXED — JK-Forum.comforum
- P0456 Evap Small Leak Code (Solved) — Jeep Wrangler TJ Forum & Communityforum
- Jeep Wrangler P0457: EVAP System – Leak Detected (causes, ESIM, gas cap, diagnostic order) — Drivetrain Resourcearticle
- P0456 on 2012-2019 Jeep Wrangler: EVAP Small Leak Causes and Fixes — Go-Parts.comarticle
- Jeep Wrangler (2003-2019) EVAP Leak Detection Pump Guide (ESIM location, DIY <30 min) — Go-Parts.comarticle
- 2007-2021 Jeep Wrangler Leak Detection Pump — Standard Motor Products LDP14 — PartsGeekarticle
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 $450 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.
Looking for P0455 on a different make?
View P0455 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.