P0455 on 2008-2014 Dodge Avenger: EVAP Large Leak Causes and Fixes

What's Unique About the 2008-2014 Dodge Avenger

On this generation of Dodge Avenger, like many Chrysler products of the era, the EVAP system uses a component called an Evaporative System Integrity Module (ESIM) or Leak Detection Pump (LDP) to test the system's integrity. This module is mounted directly on the charcoal canister near the fuel tank and is a very common failure point. The internal valve can fail, creating the large leak that triggers the code. While a loose gas cap is always the first suspect, a faulty ESIM/LDP or a stuck-open purge valve are frequent culprits on these specific vehicles.

Symptoms You May Notice

• Check Engine Light is on
• A faint smell of fuel, especially around the rear of the vehicle or in the garage after being parked.
• Remote start may be disabled by the system when a Check Engine Light is active.
• A whooshing sound may be heard or a fuel odor noticed when inspecting the EVAP system hoses.

Most Likely Causes

1. Loose, Damaged, or Incorrect Gas Cap 🔴 High Probability This is the most common cause for a P0455 code on any vehicle, as the cap seal can degrade over time or simply not be tightened correctly after refueling. Even the tether getting caught under the cap can break the seal and cause the code.
   How to confirm: Inspect the gas cap for cracks or damage to the rubber O-ring seal. Ensure it is tightened until it clicks at least once. If the cap looks worn or damaged, it's an inexpensive and easy first replacement. An OEM Mopar cap is recommended for best fit.
   Typical fix: Tighten or replace the gas cap.
   Est. part cost: $15-$35
2. Faulty EVAP Leak Detection Pump / ESIM 🟡 Medium Probability The ESIM (Evaporative System Integrity Module), also called a Leak Detection Pump, is a known failure point on many Chrysler/Dodge vehicles of this era. It's a single assembly that often contains the vent valve and pressure sensor. The internal valve can fail, creating a large leak.
   How to confirm: The ESIM is located near the fuel tank, mounted on the charcoal canister. Diagnosis can be tricky without a scan tool, but it's a high-probability part to fail after the gas cap is ruled out. A smoke test is the definitive way to confirm a leak at this component or its seals.
   Typical fix: Replace the ESIM assembly. This involves lowering the charcoal canister, giving the old ESIM a quarter-turn to remove it, and installing the new one.
   Est. part cost: $50-$100
3. Faulty Purge Valve/Solenoid 🟡 Medium Probability The purge valve, located in the engine bay, can get stuck open, creating a constant vacuum leak into the EVAP system and triggering a large leak code. This is a common failure item on the 2.4L engine. 🎬 Watch: Step-by-step purge valve replacement for the 2.4L engine.
   How to confirm: Remove the purge valve from its bracket in the engine bay. It should be normally closed. Try to blow air through either port; if you can blow through it, it is stuck open and needs to be replaced.
   Typical fix: Replace the purge valve solenoid.
   Est. part cost: $25-$50
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Rubber and plastic hoses become brittle with age and exposure to the elements, leading to cracks, especially at connection points near the engine or canister.
   How to confirm: Visually inspect all accessible EVAP lines running from the fuel tank to the charcoal canister and up to the engine bay. A smoke test is the most effective method, where low-pressure smoke is introduced into the system via the service port, and any leaks become visible.
   Typical fix: Replace the cracked or damaged section of hose.
   Est. part cost: $5-$20

Rare But Worth Checking

• Cracked Charcoal Canister: The plastic housing of the charcoal canister can crack due to road debris impact or age, creating a large leak. This is usually found during a visual inspection or with a smoke test.
• Damaged Fuel Filler Neck: Rust or physical damage can compromise the sealing surface where the gas cap sits, preventing a proper seal and causing a P0455 code. This is more common in salt-belt regions.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0455 is present.
2. Inspect the gas cap. Remove it, check for cracks or a worn seal, and then reinstall it, ensuring it clicks several times. Check that the tether is not caught under the seal.
3. Clear the code with the scanner and drive for a few days. The EVAP monitor typically runs when the fuel level is between 1/4 and 3/4 full. If the code does not return, the issue was a loose gas cap.
4. If the code returns, locate the purge valve in the engine bay, near the intake manifold. Disconnect its hoses and electrical connector. Try to blow through it. If air passes through, it's stuck open and must be replaced.
5. If the purge valve is good, visually inspect all visible EVAP hoses for obvious cracks, breaks, or disconnections, particularly around the canister and engine bay.
6. If no visible issues are found, the next most likely culprit is the Evaporative System Integrity Module (ESIM) on the charcoal canister near the fuel tank.
7. For a definitive diagnosis, perform a smoke test. A smoke machine forces low-pressure smoke into the EVAP system's service port. Smoke will exit from the location of the leak, making it easy to spot.

Technical Service Bulletins (TSBs) & Recalls

Manufacturer service bulletins for related Dodge and Chrysler platforms frequently group P0455 with other EVAP performance codes. For instance, TSB Bulletin #1809423 and TSB Bulletin #1400522REVB note that technicians may find P0455 set alongside P0456 (small leak) or P0441 (purge performance). Additionally, TSB Bulletin #1807422 suggests using the wiTECH Small Leak Verification test if multiple codes are present to isolate the failure point.

Parts You'll Likely Need

• Gas Cap (OEM #52030377AB, 98558FNGB (Mopar)) — This is the most frequent and simplest fix for a P0455 code. The seal wears out or it's improperly tightened.
  Trusted brands: Mopar, Stant, Gates, Carquest
  OEM price range: $25-$40
  Aftermarket price range: $15-$25
• EVAP Leak Detection Pump (ESIM) (OEM #4861962AA (Mopar)) — This component, also called an Evaporative System Integrity Module (ESIM), is a common failure point on Chrysler vehicles of this era, causing a large leak when its internal valve fails.
  Trusted brands: Mopar, Dorman, Standard Motor Products (SMP)
  OEM price range: $70-$120
  Aftermarket price range: $50-$90
• Canister Purge Valve / Solenoid (OEM #4891735AC, 04891735AC (Mopar)) — This valve can get stuck open, causing a constant leak that the system detects as 'large'. It's a common failure item located in the engine bay.
  Trusted brands: Mopar, Bosch, Dorman (911-481)
  OEM price range: $40-$60
  Aftermarket price range: $25-$50

Related Codes That Often Appear With This One

• P0456 — P0456 indicates a small EVAP leak. Sometimes a component is beginning to fail and may initially set a small leak code before it worsens and triggers the large leak code P0455.
• P0441 — P0441 indicates incorrect purge flow. This often points directly to a malfunctioning purge valve, which can also cause a P0455 if it's stuck open.
• P0457 — Indicates a large leak detected specifically due to a loose or missing fuel cap. If this code is present with P0455, the gas cap is almost certainly the culprit.

Mechanic-Grade Diagnostic Values

• Purge Valve Solenoid Functional Test — expected: Solenoid should be normally closed. With the valve removed from the vehicle, you should NOT be able to blow air through it.. Failure: If air can be blown through the valve when it is not energized, it is stuck open and must be replaced.
• EVAP System Pressure (via Scan Tool) — expected: When the system is sealed by the PCM for a test, the fuel tank pressure sensor should show the system holding a slight vacuum (pressure drops and holds steady).. Failure: With a P0455 large leak, the pressure will fail to drop or will drop and then return to atmospheric pressure very quickly, indicating it cannot hold a vacuum.

Scan Tool Commands That Help

• Professional Scan Tool (e.g., Witech, Autel, Snap-on): EVAP System Test / Purge/Vent Solenoid Actuation — This bidirectional command allows the technician to manually open and close the purge and vent solenoids to verify their function. You can command the vent solenoid closed and the purge solenoid open to allow a smoke machine to fill the entire system for a leak test. It is used to isolate a faulty solenoid without having to remove it from the vehicle first.

Wiring & Ground Locations

• Evap/Purge Solenoid — Located in the engine bay, at the left rear of the engine compartment.. This is a primary component for the P0455 code. Knowing its location is key for visual inspection, testing, and replacement.
• ESIM / Evap System Monitor Switch — Under the left rear of the vehicle, mounted on the charcoal canister near the fuel tank.. This is the second most likely component to fail after the gas cap. It is often replaced to fix a P0455. Its location under the vehicle requires raising it for access.
• G303 (Ground) — Location varies by year. On 2008 models, it's at the left rear quarter panel. On 2012 models, it's at the left 'B' pillar. Always verify with a diagram for your specific year.. A poor ground for the ESIM or other EVAP components can cause erratic behavior or failure, potentially leading to a false code. This is an important check if electrical issues are suspected.
• Fuel Tank Pressure Sensor — On later models (e.g., 2014), this sensor is part of the fuel pump module, located on top of the fuel tank.. While less common, a faulty pressure sensor can report a large leak when none exists. Accessing it requires dropping the fuel tank or removing the rear seat for access through the service panel.

Real Owner Repair Stories

• YouTube video 'Codigo p0455 2014 Dodge Avenger' (2014 Dodge Avenger) — Check Engine Light with code P0455.
  ❌ Tried (didn't work) The video starts with diagnosis, not failed attempts.
  ✅ What actually fixed it A smoke test revealed that an EVAP line running from the fuel tank to the engine had been rubbing against the transmission shifter cable, causing a hole to be worn into the line. The fix was to repair the damaged section of the EVAP line.
• NHTSA ODI #11204850 — An owner of a related Dodge vehicle reported a P0455 check engine light caused specifically by a cracked EVAP purge hose.
• NHTSA ODI #10561465 — One owner reported that after a P0455 code appeared, a dealer ran an ESIM test and vacuum test with no results, initially suggesting the cause was likely a loose gas cap.

OEM Part Supersession History

• 4861962AA → 04861962AD — Part has been revised and updated by the manufacturer over time. The supersession chain is 4861962AA -> 4861962AB -> 4861962AC -> 04861962AD.
  Heads up: The newest part number (04861962AD) is the correct replacement for all previous versions and should be used for repairs.
• 4891735AC (Purge Valve) → 4891735AD — Manufacturer revision.
  Heads up: Some Mopar catalogs incorrectly list this part as the entire throttle body assembly, which has been discontinued. The purge valve for the Avenger is a separate, small solenoid located in the engine bay, not part of the throttle body itself. Ensure you are buying the standalone solenoid, not searching for a throttle body.

Model Year Variations Within This Range

• 2008-2010: These early models are known for widespread electrical issues, most notably related to the Totally Integrated Power Module (TIPM). A faulty TIPM can cause a cascade of seemingly unrelated codes and problems, including potential power issues to EVAP components. These years also had significant powertrain and interior quality issues.
• 2011-2014: The 2011 model year was a major refresh with a new interior, a new optional 3.6L Pentastar V6, and heavily revised suspension. Reliability is generally considered much better for these later years. While the EVAP system is functionally similar, some wiring and ground locations may differ from pre-refresh models (e.g., G303 ground point).

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Electronic Throttle Body (ETB) Failure 🔴 High — Very common. Often causes the 'Electronic Throttle Control' (lightning bolt) light, limp mode (won't accelerate past 15 mph), and rough idle.
• Alternator / Charging System Failure 🟠 Medium — Common failure item. Symptoms include a battery light, flickering headlights/interior lights, and eventual stalling or no-start conditions. On these vehicles, the PCM controls voltage regulation, so sometimes the PCM itself is the cause of overcharging.
• 62TE Automatic Transmission Problems 🔴 High — Affects models with the 6-speed automatic. Issues include harsh shifting, slipping between gears, stalling when put into drive, and entering 'limp mode'. Problems are often traced to the solenoid pack or internal valve body wear.
• Front/Rear Subframe Corrosion 🔴 High — Significant rust perforation can occur on the front and rear crossmembers, particularly in salt-belt regions. This can lead to popping noises and, in severe cases, structural failure. (Ref: Chrysler extended the warranty to 10 years for this issue (X69 Warranty Extension) and issued TSB 23-007-17 REV. B for inspection and replacement.)
• Thermostat Failure 🟡 Low — The thermostat, often sold as a complete plastic housing, is known to fail, leading to a check engine light or lack of heat.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used part can be a cost-effective choice for larger, less failure-prone components like the charcoal canister or the fuel filler neck. These parts rarely fail unless physically damaged.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For fuel filler necks, inspect the gas cap sealing surface for any rust, pitting, or damage.
• For charcoal canisters, ensure the plastic housing has no cracks, especially around the hose fittings.
• Check that all plastic hose connectors and clips on any used part are intact and not brittle.
• Prioritize donors from dry, non-salt-belt climates to minimize rust and plastic degradation.

OEM-only on this vehicle (don't cheap out):

• Gas Cap: Aftermarket caps can have sealing issues. An OEM Mopar cap is strongly recommended to ensure a perfect seal and avoid a recurring code.

Aftermarket brands forum-validated for this vehicle:

• Dorman
• Standard Motor Products (SMP)
• Bosch

Brands owners have reported issues with on this vehicle:

• No-name, unbranded parts from online marketplaces, especially for electronic components like the ESIM and purge valve, as their quality and durability can be highly questionable.

Real Owner Stories

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

Related OBD-II Codes

• P0442 — Often diagnosed alongside P0455; while P0455 is a large leak, P0442 represents a small leak often caused by the same components like a degrading gas cap or a failing ESIM/Leak Detection Pump.
• P0496 — Related to the purge valve solenoid; if the purge valve is stuck open (a common failure on the 2.4L engine), it can trigger EVAP flow codes or large leak codes like P0455.
• P0507 — Can occur if the purge valve is stuck open, as this creates a constant vacuum leak into the engine, potentially affecting idle speed.
• P2173 — A high airflow/vacuum leak code that may appear if there is a significant failure in the intake or EVAP system, often associated with the Electronic Throttle Control issues common to this vehicle.

Frequently Asked Questions