P0455 on 2016-2022 Dodge Challenger: EVAP Large Leak Causes & Fixes

What's Unique About the 2016-2022 Dodge CHALLENGER

For Dodge vehicles, including the Challenger and its platform mates the Charger and 300, the EVAP system components are fairly standard Mopar parts. However, owner forums and mechanic videos frequently point towards three primary culprits for P0455: the gas cap, the purge valve in the engine bay, and the Evaporative System Integrity Monitor (ESIM) switch on the charcoal canister. The ESIM, which replaces a traditional vent valve on many modern Chrysler products, is a known failure point that can get stuck or fail its internal switch, causing the system to report a large leak.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on.
• A noticeable smell of fuel, especially around the rear of the car or near the gas cap.
• A "Loose Fuel Cap" message may appear on the dashboard display.
• Difficulty starting immediately after refueling (less common, but can be caused by a stuck-open purge valve).
• Slightly decreased fuel economy due to escaping fuel vapors.

Most Likely Causes

1. Loose, Damaged, or Incorrect Gas Cap 🔴 High Probability This is the most frequent cause for any P0455 code. The cap's seal can degrade over time, or it may simply not have been tightened correctly after refueling. Many owners on forums report fixing the code simply by replacing the cap.
   How to confirm: Inspect the gas cap for cracks or damage to the rubber O-ring. Ensure it is tightened until it clicks at least once. If the cap looks worn, replacement is a cheap and effective first step. A cracked gasket on the cap is a common failure point.
   Typical fix: Tighten or replace the gas cap.
   Est. part cost: $20-$40
2. Faulty EVAP Purge Valve/Solenoid 🟡 Medium Probability The purge valve, located in the engine bay, can get stuck open, creating a constant vacuum leak from the EVAP system into the intake manifold. This is a very common failure on many Chrysler/Dodge vehicles.
   How to confirm: With the engine off, disconnect the valve and try to blow through it. It is a normally closed valve, so if air passes through, it is stuck open and needs to be replaced. You can also test it with a hand vacuum pump to see if it holds vacuum.
   Typical fix: Replace the EVAP purge valve. The Mopar part number is often cited as 04627694AB for many Challenger models, but always verify with your VIN.
   Est. part cost: $25-$60
3. Faulty Evaporative System Integrity Monitor (ESIM) Switch 🟡 Medium Probability This component, often called a leak detection pump, replaces the traditional vent valve on these vehicles. It is mounted on the charcoal canister and is responsible for sealing the system for tests. Its internal diaphragm or switch can fail, causing it to be unable to seal the system, thus flagging a large leak.
   How to confirm: This part is located behind the passenger-side rear wheel well liner. It can be tested with a scan tool or manually with a power probe and vacuum/pressure. A common failure mode is the internal switch failing to close when vacuum is applied. A smoke test will show smoke exiting the ESIM's filter if it's stuck open.
   Typical fix: Replace the ESIM assembly. The Mopar part number is often 4861962AA (or subsequent revisions like AB, AC, AD). It's critical to install the new part in the correct orientation (connector at the 3 o'clock position) or it will not function.
   Est. part cost: $40-$100
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Rubber and plastic hoses become brittle over time due to heat and exposure, leading to cracks. A large enough crack will trigger the P0455 code. The hoses connected to the purge valve and the ESIM are common places to check.
   How to confirm: Visually inspect all accessible EVAP lines running from the engine bay to the charcoal canister near the tank. The definitive method is to use a smoke machine, which fills the system with a visible vapor to pinpoint the exact location of the leak.
   Typical fix: Replace the cracked or broken section of hose.
   Est. part cost: $10-$50

Rare But Worth Checking

• Cracked Charcoal Canister: The canister itself can be damaged by road debris or develop internal faults, causing a large leak. This is uncommon but should be checked if other components are fine. A user on a Reddit thread for a Chrysler 300 fixed their EVAP issue by replacing the entire canister assembly.
• Damaged Fuel Filler Neck: Rust or damage to the metal filler neck where the gas cap seals can prevent a proper seal, even with a new cap. This is a known issue on other vehicles and can be diagnosed by a smoke test showing smoke escaping from the gas cap area even with a new, tight cap.
• Faulty Fuel Tank Pressure Sensor: In rare cases, the sensor that measures system pressure may fail and send incorrect data to the computer, falsely triggering the code. This often sets other sensor-specific codes as well.

Diagnosis Steps

1. Check the gas cap. Remove it, inspect the seal for damage, and reinstall it, ensuring it clicks several times. Clear the code and drive for a few days to see if it returns.
2. If the light returns, visually inspect the EVAP purge valve and its connecting hoses in the engine bay for any obvious cracks or disconnections.
3. Perform a manual test on the purge valve. With the engine off, remove the valve and try to blow through it. If air passes, it's stuck open and faulty.
4. Inspect the fuel filler neck for any signs of rust or damage that could prevent the gas cap from sealing properly.
5. Locate the ESIM switch and charcoal canister assembly, typically behind the rear passenger-side wheel well liner. Inspect for any physical damage.
6. If no obvious issues are found, the most effective next step is to have a smoke test performed. This test introduces low-pressure smoke into the EVAP system, and any leaks will be made visible as the smoke escapes from a cracked hose, faulty valve, or bad seal.
7. If a scan tool is available, use it to monitor the ESIM switch status while applying vacuum to the system to see if the switch closes as expected.
8. Based on the smoke test or component test results, replace the leaking part.
9. After repair, clear the code with a scan tool and perform a drive cycle to allow the EVAP monitor to run and confirm the fix.

Parts You'll Likely Need

• Fuel Cap — This is the most common failure point for a P0455 code due to a worn seal or improper tightening.
  Trusted brands: Mopar, Stant
  OEM price range: $30-$45
  Aftermarket price range: $15-$25
• EVAP Purge Valve / Solenoid (OEM #04627694AB) — This valve frequently gets stuck open, causing a large leak code. It's a common point of failure on many vehicles, including the Challenger.
  Trusted brands: Mopar, Bosch, Dorman
  OEM price range: $40-$70
  Aftermarket price range: $25-$50
• Evaporative System Integrity Monitor (ESIM) Switch (OEM #4861962AD) — This switch, which acts as the system's vent and leak detector, is a known high-failure item on this platform. It gets stuck or the internal switch fails.
  Trusted brands: Mopar, Duralast
  OEM price range: $75-$110
  Aftermarket price range: $40-$60

Related Codes That Often Appear With This One

• P0456 — This code for a 'small leak' can appear alongside P0455, or one may lead to the other as a leak worsens. The provided TSBs list them together frequently. [Bulletin #1809623, #1400522REVB, #1807422, #1807517, #18-062-17]
• P0441 — Indicates 'Incorrect Purge Flow', often caused by a faulty purge valve, which is also a common cause for P0455. [Bulletin #1809623, #1807517, #18-062-17]
• P0440 — A general EVAP system failure code that can be triggered along with more specific leak codes like P0455. [Bulletin #1809623, #1807422]
• P0457 — Indicates a large leak was detected, often specifically attributed to a loose fuel cap. It frequently appears with P0455 and P0456.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #1809623: For 2022 models, notes that MIL illumination may be caused by P0455, P0456, P0440, or P0441, often related to PCM software logic.
• Bulletin #1400522REVB: For 2021 models, lists P0455 and P0456 among other EVAP codes that may be set due to a software issue requiring a PCM update.
• Bulletin #1807422: For 2019 models, mentions P0455 along with other EVAP codes and suggests using specific diagnostic routines in the wiTECH scan tool.
• Bulletin #1807517: For 2016 models, this TSB is a broad PCM software update to address a wide range of potential DTCs, including P0455, P0441, and P0456. [Bulletin #1807517]
• Bulletin #18-062-17: For 2016 models, another PCM software update aimed at improving diagnostic logic for various codes, including P0455 and P0456. [Bulletin #18-062-17]

Platform-Specific Known Issues

• ESIM Failure and Incorrect Installation: The Evaporative System Integrity Monitor (ESIM) is a well-documented failure point for P0455 on this platform. It replaces the older style vent solenoid. When replacing it, it is critical to install it in the correct rotational position. The electrical connector must be at the 3 o'clock position for the internal weights to function correctly. Incorrect installation will cause the new part to fail the system test immediately.

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure (FTP) Sensor 5V Reference — expected: ~5.0 Volts DC. Failure: A reading of 0V or significantly less than 5V indicates a broken wire or a fault in the PCM.
• Fuel Tank Pressure (FTP) Sensor Signal Voltage — expected: Varies between ~0.5V and ~4.5V depending on tank pressure. A normal reading with the gas cap off (atmospheric pressure) is often around 2.5V-2.6V.. Failure: Voltage is stuck at 0V, 5V, or does not change when pressure/vacuum is applied to the tank.
• ESIM (Leak Detection Pump) Switch Test — expected: With the ESIM connected electrically but removed from the canister, applying ground to one pin should allow ground to pass through to the other pin only when pressure or vacuum is applied to the appropriate port, simulating a sealed system.. Failure: If ground does not pass through when pressure/vacuum is applied, or if it passes through with no pressure/vacuum, the internal switch is bad.

Scan Tool Commands That Help

• wiTECH (OEM Dodge/Chrysler Scan Tool): Small Leak Verification Test (SLVT) — This is the mandatory factory procedure to verify if a small leak (P0456) is present before and after a repair. While P0455 is a large leak, running this test can help confirm the integrity of the system after a repair, as a road test alone is not sufficient to confirm the fix.
• Professional Scan Tool (e.g., Autel, Snap-on): EVAP System Test / Vent Solenoid Command — Used during a smoke test to command the EVAP vent solenoid (or ESIM) closed, sealing the system. This allows the smoke to build pressure and reveal leaks. Without this command, smoke will simply exit through the normally open vent.

Wiring & Ground Locations

• G304 — In the trunk, behind the right-side trim panel, near the rear fuse box and battery.. This is a major body ground point for multiple rear-mounted components. While not directly tied to the EVAP system in all diagrams, a poor ground here can cause a host of difficult-to-diagnose electrical issues with nearby modules and sensors, including those related to the fuel tank and EVAP system.
• EVAP Purge Valve Connector — On the engine, typically near the intake manifold.. This 2-pin connector provides power and control signal to the purge valve. One pin should have 12V (battery voltage) with the key on, and the other is ground-side controlled by the PCM. Checking for voltage here is a primary step in diagnosing a non-responsive purge valve.
• Fuel Tank Pressure (FTP) Sensor Connector — On the fuel tank or fuel filler neck.. This 3-pin connector provides the sensor with a 5V reference, a ground, and sends the signal back to the PCM. A break in any of these wires (especially the 5V reference or ground) will cause sensor-related fault codes and prevent the EVAP monitor from running correctly.

Real Owner Repair Stories

• Reddit user in r/Challenger (Dodge Challenger (year not specified, but modern)) — P0456 (Small EVAP Leak) code.
  ❌ Tried (didn't work) Replacing the gas cap., Replacing the purge valve under the hood.
  ✅ What actually fixed it The problem was finally solved by replacing the Evaporative System Integrity Module (ESIM), also called a leak detection pump. The user noted the original part was 'completely broken inside'.
• Reddit user in r/Challenger (2011 Challenger 392) — EVAP leak code (specific code not mentioned).
  ❌ Tried (didn't work) Initial visual inspection did not reveal the leak source.
  ✅ What actually fixed it After performing a smoke test by plumbing into the fuel filler neck, the leak was found at the leak detection pump (ESIM) located in the passenger side rear wheel well. The user replaced both the ESIM and the charcoal canister to resolve the issue.

"I Checked Everything" — The Actual Cause

• In many modern Chrysler/Dodge vehicles, a smoke test may show no leaks, yet a P0455 or P0456 code persists. This often points to a faulty Evaporative System Integrity Monitor (ESIM). The ESIM's internal switch can fail to report the system's status correctly to the PCM, even if the system is physically sealed. The PCM interprets this lack of signal as a large leak, triggering the code. A technician confirmed this is a high-failure-rate part and is often the cause when a smoke test passes.

OEM Part Supersession History

• 4861962AA, 4861962AB, 4861962AC → 4861962AD — Part has been revised and updated by the manufacturer over time to improve reliability.
  Heads up: The revisions (AA, AB, AC, AD) are generally interchangeable for the specified applications, with the latest version (AD) being the recommended replacement.
• 4627694AA → 04627694AB — Standard part number revision by Mopar.
  Heads up: The new part number (ending in AB) directly replaces the old one (ending in AA).

Model Year Variations Within This Range

• 2015+: Models from 2015 onward are more likely to use the ESIM (Evaporative System Integrity Monitor) system for leak detection, which is a common failure point. Earlier models may have used a different style of Leak Detection Pump (LDP) and vent solenoid, which have different diagnostic procedures.
• 2021+: Some newer models may have slightly different fuse and relay locations in the rear Power Distribution Center (PDC) in the trunk compared to earlier models in the 2016-2020 range. Always verify fuse locations with the fuse box cover diagram.