P0455 on 2012-2013 Infiniti M56: EVAP Gross Leak Causes and Fixes

What's Unique About the 2012-2013 Infiniti M56

Like many Nissan and Infiniti vehicles of this era, the M56's EVAP system components, particularly the vent control valve, are susceptible to failure. This valve is mounted on the charcoal canister at the rear of the vehicle, where it is exposed to road debris and moisture. This exposure can lead to internal corrosion or cause the valve's plunger to stick open, creating the large leak detected by the system. Infiniti has issued several informational bulletins for all its 2012 and newer vehicles regarding EVAP leak codes, including P0455, which underscores how common this issue is across the brand. The problem is also rampant on platform-mates like the Infiniti QX80 and Nissan Titan, which share the same engine family and EVAP design.

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 (Malfunction Indicator Lamp) is on
• A noticeable fuel smell, especially around the rear of the vehicle
• A "Loose Fuel Cap" warning message on the instrument cluster
• Difficulty refueling (gas pump nozzle shuts off repeatedly before the tank is full)

Most Likely Causes

1. Loose or Faulty Fuel Filler Cap 🔴 High Probability → Shop Fuel Tank Cap This is the most common cause for P0455 on any vehicle. The gas cap is a critical seal for the EVAP system. An improperly tightened cap, a worn-out seal, or a tether getting caught under the cap can cause a large leak. Infiniti TSB ITB13-044J specifically calls this out as a primary cause.
   How to confirm: Ensure the cap is tightened until it clicks at least once. Inspect the rubber seal for cracks, stiffness, or debris. If the seal is damaged or the cap is suspect, replacement is the best confirmation. Many owners report that only an OEM cap will reliably solve the issue. 🎬 Watch: A very easy fix for the P0455 code.
   Typical fix: Tighten or replace the fuel filler cap. It is highly recommended to use an OEM (Original Equipment Manufacturer) cap, as some aftermarket caps do not seal correctly, leading to the code returning.
   Est. part cost: $25-$50
2. Failed EVAP Canister Vent Control Valve (Solenoid) 🔴 High Probability → Shop Vapor Canister Vent Valve This valve is a known failure point on many Nissan/Infiniti models. Located on the EVAP canister near the rear axle, it's exposed to the elements, causing it to corrode and stick open, creating a permanent large leak. The part has been superseded multiple times by Nissan/Infiniti, indicating design revisions to address the failures.
   How to confirm: The valve is normally open and should close when 12V is applied. It can be removed and bench-tested; if you can blow through it when 12V is applied, it has failed. A more definitive diagnosis is a smoke test, which will show smoke exiting from the failed, stuck-open valve. A professional scan tool can also command the valve closed to check its function. The valve is located on the rear passenger side behind the tire; the charcoal canister may need to be unbolted and lowered to provide enough clearance to twist and remove the valve.
   Typical fix: Replace the EVAP canister vent control valve. The part twists into the charcoal canister. A new O-ring should come with the replacement valve. Access involves removing a plastic shield and often lowering the canister itself by removing a single 12mm bolt. 🎬 See this walkthrough on replacing the vapor canister vent solenoid.
   Est. part cost: $50-$120
3. Cracked or Disconnected EVAP Hose 🟡 Medium Probability Rubber hoses can become brittle and crack over time due to age and heat cycles. A large hose, such as the one connecting the fuel filler neck to the tank or the main line to the canister, can come loose or split.
   How to confirm: A visual inspection of all accessible EVAP lines from the engine bay to the fuel tank is the first step. A smoke test is the most effective method to pinpoint the exact location of a hose leak.
   Typical fix: Replace the cracked or damaged section of the hose and secure it with clamps.
   Est. part cost: $15-$75

Rare But Worth Checking

• Failed EVAP Canister Purge Volume Control Valve: → Shop Vapor Canister This valve is located in the engine bay and is less likely to cause a large leak than the vent valve. It typically fails by sticking closed or having a weak solenoid, but can sometimes stick open. It may also be accompanied by other codes like P0444 or P0445.
• Cracked EVAP (Charcoal) Canister: → Shop Vapor Canister The plastic housing of the canister itself can crack from physical impact (like road debris) or age, creating a large leak. This is usually found during a smoke test after the more common components are checked.
• Damaged Fuel Filler Neck: → Shop Fuel Filler Neck Corrosion or damage to the metal fuel filler neck, especially in regions that use road salt, can prevent the gas cap from sealing properly, leading to a persistent P0455 code even with a new cap.

Diagnosis Steps

1. Check the gas cap. Remove it, inspect the seal for damage, and retighten it until it clicks. Clear the code and drive for a few days to see if it returns. Per TSB ITB13-044J, a test drive is not part of the official diagnostic procedure; the system will re-test on its own.
2. If the code returns, consider replacing the gas cap with a new OEM part, as worn seals are not always visually obvious and aftermarket caps are unreliable.
3. If the code persists, perform a thorough visual inspection of all accessible EVAP hoses and lines between the engine bay and the fuel tank. Look for obvious cracks, disconnections, or damage.
4. Locate the EVAP canister vent control valve on the charcoal canister at the rear of the vehicle, on the passenger side. Inspect it and its electrical connector for corrosion or damage.
5. If the leak source is not obvious, the most effective next step is to have a professional perform a smoke test. This involves injecting pressurized smoke into the EVAP system to quickly and accurately reveal the source of the leak.
🎬 Watch: How to find and fix large EVAP leaks on your car.
6. Based on the smoke test results or a direct test of the component, replace the faulty part. This is most often the vent control valve, a cracked hose, or the charcoal canister itself.

Parts You'll Likely Need

• Fuel Filler Cap (OEM #17251-1NM0F) — This is the most frequent and simplest fix for a P0455 code. The seal wears out over time, causing a leak. Using an OEM cap is recommended for a proper seal.
  Trusted brands: Infiniti (OEM)
  OEM price range: $30-$50
  Aftermarket price range: $15-$30
• EVAP Canister Vent Control Valve (OEM #14935-JF00B (supersedes 14935-AM60B, 14935-JF00A; may be superseded by 14935-JF00E, 14935-JF02C)) — This is a very common failure point on Infiniti vehicles. It gets stuck open due to corrosion from its exposed location at the rear of the car, causing a large leak. The multiple part number supersessions indicate it's a known issue that the manufacturer has tried to correct.
  Trusted brands: Hitachi (OEM Manufacturer), Dorman (e.g., 911-503), Standard Motor Products (e.g., CP656)
  OEM price range: $80-$120
  Aftermarket price range: $30-$70

Related Codes That Often Appear With This One

• P0456 — This code indicates a 'very small leak'. It can appear alongside or intermittently with P0455 if a component is in the process of failing, creating leaks of varying sizes. Infiniti TSBs group these codes together.
• P0442 — This code indicates a 'small leak'. Like P0456, it points to a leak in the same system and is often caused by the same failing components. The TSBs from Infiniti group these three codes together.

Technical Service Bulletins (TSBs) & Recalls

• ITB13-044J
• ITB13-044g

Platform-Specific Known Issues

• Infiniti has issued multiple Technical Service Bulletins (TSBs), including ITB13-044J and ITB13-044g, that apply to all 2012 and newer models for EVAP leak codes P0442, P0455, and P0456. These bulletins guide technicians on proper diagnosis, starting with the fuel cap, and explicitly state that a 'test drive is not part of the DTC confirmation or diagnostic procedures for these DTCs' and that 'Test-driving the vehicle for these DTCs will only waste time.' They emphasize using a smoke machine for an effective repair.

Mechanic-Grade Diagnostic Values

• EVAP Canister Vent Control Valve harness connector voltage — expected: ~12V (battery voltage). Failure: If battery voltage is not present at one of the two pins with the ignition on, it indicates a wiring or fuse issue upstream of the valve.
• EVAP Canister Purge Valve solenoid resistance — expected: Typically 15 to 30 Ohms for most vehicles.. Failure: A reading far outside this range, or an open circuit, indicates a failed solenoid coil within the valve.

Scan Tool Commands That Help

• Infiniti CONSULT-III plus: EVAP System Leak Check (Active Test) — This function is used to verify a repair without waiting for a full drive cycle. The tool commands the EVAP system to seal itself, allowing the technician to monitor the system's pressure-holding ability directly on the scan tool.
• Infiniti CONSULT-III plus: Close Vent Control Valve — This specific command is essential during a smoke test. By manually forcing the vent valve closed, the technician can introduce smoke and ensure the entire system is sealed for an accurate test, preventing smoke from escaping through the normally open vent path.

Wiring & Ground Locations

• EVAP Control System Pressure Sensor — Under the right rear of the vehicle, connected to the EVAP canister.. This sensor reports the pressure/vacuum in the EVAP system to the ECM. A faulty sensor could provide incorrect data, leading to a false P0455 code. Its location is confirmed in wiring diagrams for the 2012 M56.
• Engine Bay Ground Points — Multiple points on the driver's side of the engine bay, including on the block and the strut tower.. While not directly for the rear-mounted vent valve, corroded engine bay grounds can cause a variety of electrical issues. The EVAP purge valve, located in the engine bay, relies on a good ground. Cleaning these grounds is a known general maintenance item for the Y51 platform.

Real Owner Repair Stories

• Infiniti Scene Forum user (Infiniti FX (similar EVAP design)) — P0455 code and occasional difficulty filling the fuel tank.
  ❌ Tried (didn't work) Replacing the fuel filler cap with a new OEM part.
  ✅ What actually fixed it Replacing the EVAP canister vent control valve (P/N 14935-JF00B) solved the check engine light. The owner noted that after the fix, the gas pump would prematurely shut off for the first few fill-ups, but the P0455 code did not return after 5,500 miles.
• G35Driver Forum user 'sonors' (2008 Infiniti G35 Sedan, 99k miles) — Persistent P0455 code, sometimes had issues with gas nozzle shutting off before the tank was full.
  ❌ Tried (didn't work) Mechanic replaced the gas cap., Owner replaced the gas cap again with a new OEM part.
  ✅ What actually fixed it The owner replaced the canister purge valve (solenoid) for less than $30, which resolved the P0455 code.

"I Checked Everything" — The Actual Cause

• In some cases across various makes, a smoke test may show no leaks, yet a P0455 code persists. A documented but rare cause for this scenario is a faulty Fuel Tank Pressure (FTP) sensor. The sensor fails to correctly report the system's pressure changes to the ECM. The ECM interprets the lack of a changing signal during the self-test as a failure to hold vacuum (a large leak), even though the system is mechanically sealed. The fix is to replace the FTP sensor itself.

OEM Part Supersession History

• 14935-AM60B → 14935-JF00A, then 14935-JF00B, then 14935-JF00E, and finally 14935-JF02C — The EVAP Canister Vent Control Valve has been updated multiple times by Nissan/Infiniti to improve reliability. The original parts were prone to the internal solenoid sticking open due to dirt and moisture ingress.
  Heads up: The newer parts are visually different but are direct replacements designed to be more durable. Always use the latest available part number for the repair.

Model Year Variations Within This Range

• 2012-2013: There are no significant changes reported for the EVAP system between the 2012 and 2013 Infiniti M56 models. Both were part of the same generation before the rebranding to Q70 and share the same components and known issues.