P0455 on 2007-2017 Jeep Patriot: EVAP Large Leak Causes and Fixes

What's Unique About the 2007-2017 Jeep Patriot

The Jeep Patriot, and its platform mates the Jeep Compass and Dodge Caliber, use a component for leak testing often called a Leak Detection Pump (LDP) but more accurately named an Evaporative System Integrity Module (ESIM) on this specific platform. This module is a known high-failure item. Beyond the ESIM, owners frequently report that the most common culprits for a P0455 code are simple mechanical failures like a bad gas cap, a cracked purge valve solenoid in the engine bay, or a fuel filler neck that has rusted out—a very common issue in regions that use road salt, with numerous owner reports online.

Symptoms You May Notice

• Check Engine Light is on
• A faint smell of gasoline, especially near the rear of the vehicle or after refueling.
• Difficulty filling the fuel tank without the pump shutting off repeatedly (if the charcoal canister is clogged or the vent is blocked).
• A "gas cap" message may appear on the dashboard, even if the cap is tight.

Most Likely Causes

1. Loose, Damaged, or Incorrect Gas Cap 🔴 High Probability The gas cap seal is a simple rubber component that degrades over time, and it is the most common point of failure for the EVAP system. Aftermarket caps are also frequently reported as not sealing as well as the OEM Mopar part.
   How to confirm: Check if the gas cap is tight (clicks at least once). Visually inspect the rubber seal on the cap for cracks, stiffness, or damage. Ensure it is the correct OEM or equivalent cap.
   Typical fix: Tighten or replace the gas cap. An OEM Mopar cap is recommended.
   Est. part cost: $15-$35
2. Cracked or Rusted Fuel Filler Neck 🟡 Medium Probability The metal fuel filler neck is highly susceptible to rust and corrosion, especially in areas with road salt, leading to pinholes or large cracks that cause a significant EVAP leak. This is a widely documented failure on Patriot/Compass forums.
   How to confirm: Remove the driver's side rear wheel and wheel well liner to visually inspect the entire length of the filler neck for rust, holes, or wet spots from fuel. A smoke test will definitively show leaks from this area.
   Typical fix: Replace the fuel filler neck assembly. Aftermarket parts from brands like TRQ and Dorman are widely available. 🎬 Watch: Step-by-step guide to replacing a rusted fuel filler neck.
   Est. part cost: $70-$150
3. Faulty EVAP Purge Valve/Solenoid 🟡 Medium Probability This solenoid, located in the engine bay, cycles frequently and can fail by getting stuck open, creating a constant leak path from the EVAP system to the engine intake. This can sometimes trigger a P0441 code as well.
   How to confirm: The purge valve is located on the driver's side of the engine bay near the firewall. With the engine off, disconnect the hose leading to the intake manifold and try to blow through the valve. If air passes through, it is stuck open and needs replacement.
   Typical fix: Replace the canister purge valve. This is a relatively simple repair documented in several DIY videos. 🎬 See how to replace the purge solenoid to fix a P0455.
   Est. part cost: $40-$85
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Rubber hoses and plastic lines, particularly in the engine bay and around the charcoal canister, become brittle over time due to heat and age and can develop cracks.
   How to confirm: Visually inspect all accessible EVAP lines in the engine bay and around the charcoal canister for obvious cracks, breaks, or loose connections. A smoke test is the most effective way to find a small crack in a hose.
   Typical fix: Replace the damaged section of hose.
   Est. part cost: $10-$50
5. Damaged EVAP (Charcoal) Canister ⚪ Low Probability The canister is a plastic box located behind the driver's side rear wheel, making it susceptible to damage from road debris or cracking with age.
   How to confirm: Visually inspect the canister for any physical cracks or damage. If you have difficulty filling the gas tank, it may indicate the canister is saturated with fuel and needs replacement.
   Typical fix: Replace the EVAP canister. This involves removing the driver's side rear wheel and liner for access.
   Est. part cost: $120-$250

Rare But Worth Checking

• Faulty Leak Detection Pump (LDP) / ESIM: On this platform, the component is often called an Evaporative System Integrity Module (ESIM). It is mounted on the charcoal canister and is responsible for testing the system. The module itself or its seal can fail, causing it to report a leak when there isn't one, or creating a leak itself. A rattling sound when shaking the removed ESIM is a common sign of failure.

Diagnosis Steps

1. Check the gas cap. Ensure it is tight and the seal is not cracked or worn. This is the most common fix. Replacing with an OEM Mopar cap is often recommended over aftermarket.
2. If the gas cap is good, clear the code and drive for a few days to see if it returns. The EVAP monitor runs only under specific conditions, sometimes requiring several drive cycles.
3. If the code returns, perform a thorough visual inspection of all visible EVAP hoses in the engine bay, especially near the purge valve, for cracks or disconnections.
4. Inspect the purge valve in the engine bay. Disconnect it and check if it's stuck open by blowing through it. If air passes, it has failed.
5. Visually inspect the fuel filler neck for severe rust or damage. This requires removing the rear driver's side wheel and liner for a clear view. This is a very common failure point.
6. If no obvious issues are found, the most reliable method for finding the leak is to have a professional perform a smoke test. This involves filling the EVAP system with a harmless, visible smoke and watching where it escapes.

Parts You'll Likely Need

• Fuel Cap (OEM #52030377AB) — This is the most frequent cause of P0455 due to its seal wearing out over time. It's the first and cheapest part to check 🎬 Watch: A helpful overview of P0455 causes and common fixes. and replace.
  Trusted brands: Mopar, Gates, Stant
  OEM price range: $20-$35
  Aftermarket price range: $15-$25
• Canister Purge Valve / Solenoid (OEM #4891741AC (supersedes 4891741AA)) — This valve is a common failure point that gets stuck open, creating a large, permanent leak in the system.
  Trusted brands: Mopar, Dorman, Standard Motor Products
  OEM price range: $55-$85
  Aftermarket price range: $30-$60
• Fuel Filler Neck (OEM #5105806AD) — Prone to rusting through, especially in northern climates, creating a large leak that is a very common cause for P0455 on this vehicle.
  Trusted brands: Mopar, TRQ, Dorman
  OEM price range: $150-$250
  Aftermarket price range: $70-$150
• EVAP Leak Detection Pump / ESIM (OEM #W0133-3117675 (Mopar)) — Also called the Evaporative System Integrity Module (ESIM), this component is a known weak point on the platform. It can fail internally or its seal can leak, triggering EVAP codes. The Dorman 310-215 is a popular aftermarket replacement.
  Trusted brands: Mopar, Dorman, Standard Motor Products
  OEM price range: $90-$120
  Aftermarket price range: $20-$50
• EVAP Vapor Canister (OEM #68368140AC (supersedes 5147060AB)) — Can be cracked by road debris or become saturated with fuel if the tank is habitually overfilled, leading to EVAP codes and refueling issues.
  Trusted brands: Mopar, Bosch
  OEM price range: $140-$210
  Aftermarket price range: $120-$200

Related Codes That Often Appear With This One

• P0456 — This code indicates a 'small' EVAP leak. It can appear alongside P0455 if a component is failing intermittently or if the leak size is on the borderline between the computer's definitions.
• P0441 — This code means 'Incorrect Purge Flow'. A large leak from a stuck-open purge valve or a major hose break can disrupt the system's ability to draw a proper vacuum, triggering this code along with P0455.
• P0457 — This code specifically indicates 'EVAP Leak Detected (Fuel Cap Loose/Missing)'. It can appear if the gas cap is the definitive cause of the large leak.

Technical Service Bulletins (TSBs) & Recalls

• TSB #18-048-16: A Technical Service Bulletin for the 2015-2016 Compass/Patriot included a PCM software update that could resolve issues setting a P0456 code, which is related to P0455. While not a direct fix for a physical leak, it indicates that software updates can be part of the diagnostic path.

Platform-Specific Known Issues

• There was a recall for the 2008 model year concerning a fuel tank roll-over valve that could have been damaged during assembly, pote

Scan Tool Commands That Help

• wiTECH or equivalent professional scan tool: EVAP Purge Solenoid Actuation — This bidirectional control allows a technician to command the purge solenoid open and closed to check for correct mechanical and electrical operation. It can be used to see if the solenoid clicks and to seal the front part of the EVAP system during a smoke test.
• wiTECH or equivalent professional scan tool: EVAP System Test — This is an automated test routine initiated by the scan tool that directs the PCM to run its internal EVAP leak monitor procedure. This can help verify a fix without waiting for multiple natural drive cycles.
• N/A - Command Does Not Exist: EVAP Vent Solenoid / ESIM Actuation — It is critical to know that on the Jeep Patriot platform, the vent side of the canister is sealed by a mechanical Evaporative System Integrity Module (ESIM), not an electronic solenoid. Therefore, there is no bidirectional scan tool command to open or close the vent valve, which can confuse technicians. The system must be sealed manually at the ESIM for testing.

Wiring & Ground Locations

• G200 — Inside the vehicle, at the base of the driver's side (left) A-pillar, near the kick panel.. A 2014 wiring diagram explicitly lists G200 as the ground point for the 'Evap system monitor switch,' which is the ESIM. A poor connection at this ground can cause the ESIM to send incorrect data to the PCM, triggering a false EVAP code even with no physical leak.
• ECU Harness Ground — On the engine air filter box, where the main engine control unit (ECU/PCM) wiring harness is located.. A real-world repair case confirmed that a bad ground connection in this area was the sole cause of a persistent EVAP code after the gas cap and purge valve were replaced. This ground is critical for the PCM and its sensor inputs.
• G112 — In the engine compartment, on the left front inner fender.. This is a primary engine bay ground point. While not directly tied to a specific EVAP component in documentation, poor grounding here can cause a range of sensor and solenoid issues, including for the purge solenoid.

Real Owner Repair Stories

• Reddit user FaithlessnessSoggy79 on r/JeepPatriot (2015 Jeep Patriot) — Check engine light with an EVAP code was on for two years; needed to pass a vehicle inspection.
  ❌ Tried (didn't work) Replacing the gas cap, Replacing the purge solenoid canister
  ✅ What actually fixed it The problem was a ground issue. The user fixed the ground wire on the ECU cables located on top of the engine air filter box, and the code did not return after a 300km drive.
• YouTube channel 'CARMEDIX' (2017 Jeep Patriot) — Check Engine Light with code P0456 (small leak, but diagnosis is identical for P0455).
  ❌ Tried (didn't work) Initial smoke test showed a leak from the rear fender liner area.
  ✅ What actually fixed it After isolating the ESIM by clamping its hose, the rest of the system held smoke perfectly. The ESIM itself was not leaking smoke but was diagnosed as faulty by removing it and shaking it; a loud rattle from the internal plunger (compared to a silent new part) confirmed it was broken. Replacing the ESIM fixed the issue.

"I Checked Everything" — The Actual Cause

• A smoke test may show the system is perfectly sealed, yet the P0455 code persists. This often points to an electrical issue rather than a physical leak. A confirmed fix was a faulty ground wire for the ECU, which caused the computer to receive bad data from the EVAP system sensors and falsely report a leak.
• The Evaporative System Integrity Module (ESIM) itself can fail internally without causing an external smoke leak. In one documented case, the system passed a smoke test after the ESIM was isolated. The ESIM was condemned because its internal plunger was broken and rattled when shaken. This is a mechanical/electrical failure of the test component itself, not a leak in the hoses or tank it is designed to monitor.

OEM Part Supersession History

• Multiple (e.g., 5278632aa, 52030377aa) → 52030377AB — Standard part consolidation and design updates by Mopar over many years and vehicle platforms.
  Heads up: The Mopar part 52030377AB is the current recommended OEM replacement and has a long list of superseded numbers it replaces, including 4578235ab, 52030377aa, 5278632aa, 5278632ac, 5278632ad, 5278632ae, 5278632af, and 5278632ag. Using a non-OEM cap is a frequent cause of repeat P0455 codes.

Model Year Variations Within This Range

• 2007-2017: Unlike many other vehicles (including other Chrysler products) that use an electronically controlled vent solenoid, the entire Jeep Patriot generation uses a mechanical, non-commandable Evaporative System Integrity Module (ESIM) to seal the canister vent. This is a critical diagnostic difference, as a technician cannot use a scan tool's bidirectional controls to close the vent for a smoke test; it must be done manually.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0456 — EVAP System Small Leak. This code is closely related to P0455 and often appears alongside it. It is specifically addressed for the 2015-2016 Patriot in TSB #18-048-16 regarding a PCM software update.
• P0457 — EVAP System Leak Detected (Fuel Cap Loose/Off). This code frequently accompanies P0455 when the system detects a massive leak that mimics a missing or completely loose gas cap.
• P0441 — EVAP System Incorrect Purge Flow. This code is often triggered alongside P0455 when the EVAP purge valve/solenoid in the engine bay fails by getting stuck open, creating a constant leak path to the engine intake.

Frequently Asked Questions