P0456 on 2006-2010 Infiniti M45: EVAP Small Leak Causes and Fixes

What's Unique About the 2006-2010 Infiniti M45

On this specific generation of Infiniti M45 (Y50), the P0456 code is very frequently linked to a specific, documented failure point: the O-ring for the EVAP vent control valve, located on the charcoal canister at the rear of the vehicle. Infiniti issued multiple Technical Service Bulletins (TSBs), including ITB17-042, that identified the degradation of this O-ring as the primary cause of the leak. This is a crucial distinction that can save owners money, as replacing just the O-ring was the recommended fix for years. However, later TSB revisions noted the O-ring (P/N 16618-JF00A) was discontinued for individual sale, making replacement of the entire vent control valve assembly the new official repair.

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 faint fuel smell, possibly near the rear of the car by the passenger side wheel well
• Failure to pass a state emissions test
• A "Loose Fuel Cap" message may appear on the dashboard, even if the cap is tight.

Most Likely Causes

1. Loose or Faulty Fuel Cap 🔴 High Probability This is the most common cause for a P0456 code on any vehicle, including the M45. The cap's seal can degrade over time, or the cap may not have been tightened correctly after refueling. Infiniti TSB ITB09012F specifically reminds technicians to check this first. Using non-OEM gas caps is also a known cause of sealing issues.
   How to confirm: Inspect the gas cap for cracks or damage to the rubber seal. Ensure it is tightened until it clicks multiple times. Clean the sealing surface of the fuel filler neck with a cloth to remove any grit or rust that could prevent a good seal. If the cap is old or aftermarket, replacement with a genuine OEM part is a cheap and effective first step.
   Typical fix: Tighten or replace the fuel cap.
   Est. part cost: $15-$40
2. EVAP Vent Control Valve O-Ring Failure 🔴 High Probability Infiniti issued multiple TSBs (ITB17-042 series) specifically for this issue on the 2006-2010 M45 and many other Nissan/Infiniti models. The rubber O-ring that seals the valve to the charcoal canister becomes hard and brittle with age, losing its ability to maintain a seal and causing a small leak.
   How to confirm: A smoke test is the most effective method. Smoke is introduced into the EVAP system, and the technician will observe it escaping from the point where the vent control valve mounts to the EVAP canister. The canister is located at the rear of the vehicle, on the passenger side, above the suspension.
   Typical fix: Initially, the fix was to replace only the O-ring (P/N 16618-JF00A). However, later TSBs state the O-ring is no longer available separately, and the entire vent control valve assembly must be replaced. 🎬 Watch: Step-by-step walkthrough for replacing the vent control valve. The updated valve assembly part number is 14935-JF00E, which supersedes previous versions like 14935-JF00B/C.
   Est. part cost: $70-$120 for the valve assembly
3. Cracked or Disconnected EVAP Hoses 🟡 Medium Probability Rubber hoses throughout the EVAP system become brittle with age and exposure to heat cycles, leading to small, hard-to-see cracks.
   How to confirm: Visually inspect all EVAP lines running from the fuel tank and charcoal canister to the engine bay. A smoke test is the definitive diagnostic method, as it will clearly show smoke seeping from any cracks or loose connections.
   Typical fix: Replace the cracked section of hose.
   Est. part cost: $10-$50
4. Faulty EVAP Vent Control Valve / Solenoid ⚪ Low Probability While the O-ring is the more common failure point, the valve itself can fail by getting stuck open or closed, or by developing a crack in its plastic housing. Rust can also cause the valve to fail, particularly in northern climates.
   How to confirm: During a smoke test, if smoke is seen coming from the valve body itself (not the seal), the valve is faulty. It can also be tested for proper electrical function with a multimeter to check for voltage at the connector and for internal resistance.
   Typical fix: Replace the EVAP vent control valve assembly.
   Est. part cost: $70-$120

Rare But Worth Checking

• Cracked EVAP (Charcoal) Canister: The plastic housing of the canister can develop hairline cracks from age or impact from road debris. This is less common than valve or hose failures but should be carefully inspected during a smoke test if no other leak is found.
• Faulty EVAP Purge Valve: The purge valve (or purge solenoid) is located in the engine bay and controls the flow of vapors to the engine. If it sticks slightly open, it can cause a leak detectable by the system self-test. This usually triggers other codes but can sometimes manifest as P0456 alone.
🎬 See how to remove and test the purge valve.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0456 is the primary code present.
2. Inspect the fuel cap. Ensure it is tight and the seal is not cracked or worn. Clean the filler neck sealing surface. If in doubt, replace the cap with an OEM part, clear the code, and drive for a few days to see if it returns.
3. If the code returns, perform a visual inspection of all accessible EVAP hoses and connections. Look for obvious cracks or loose fittings, especially on the lines around the canister at the rear of the car.
4. The most definitive diagnostic step is to perform a smoke test. Introduce low-pressure smoke into the EVAP system via the service port.
5. Carefully observe where smoke escapes. Pay close attention to the area where the EVAP vent control valve mounts to the charcoal canister, as this is the most likely leak source according to Infiniti TSBs.
6. Also check the vent valve body itself, all hose connections, the purge valve in the engine bay, and the fuel tank filler neck for any signs of smoke.
7. Once the leak is identified, replace the faulty component. After the repair, clear the codes. The EVAP monitor may take several drive cycles to run and confirm the fix.

Parts You'll Likely Need

• Fuel Cap (OEM #17251-79960) — This is the most frequent and easiest fix for a P0456 code. The seal wears out, causing a pressure loss. An OEM cap is recommended over aftermarket options.
  Trusted brands: Infiniti (OEM), Stant, Gates
  OEM price range: $25-$40
  Aftermarket price range: $15-$25
• EVAP Vent Control Valve (OEM #14935-JF00E) — A failed O-ring at the valve's mounting point is a documented common issue on this vehicle per TSB ITB17-042. Per the latest TSBs, the valve must be replaced as an assembly because the O-ring is discontinued. This part number supersedes 14935-JF00A, 14935-JF00B, and 14935-JF00C.
  Trusted brands: Infiniti (OEM), Dorman (911-503), Standard Motor Products
  OEM price range: $90-$140
  Aftermarket price range: $40-$100
• EVAP Vent Control Valve O-Ring (OEM #16618-JF00A) — This was the original specified fix in earlier TSBs for the common leak at the vent valve. However, TSBs were later updated to state this part is no longer available for service and the entire valve should be replaced. Some dealer sites still list it, but availability is not guaranteed.
  OEM price range: $5-$15 (if found)
  Aftermarket price range: N/A

Related Codes That Often Appear With This One

• P0442 — P0442 indicates a 'medium' EVAP leak. If the small leak from P0456 worsens over time (e.g., the O-ring degrades further), it can eventually trigger a P0442 code.
• P0455 — P0455 indicates a 'large' EVAP leak. It's less common to see with P0456, but a component failure, like a valve sticking wide open, could theoretically present as different leak sizes at different times during the ECU's self-tests.

Technical Service Bulletins (TSBs) & Recalls

• ITB17-042E: DTC P0456 CAUSED BY EVAP LEAK AT VENT CONTROL VALVE O-RING
• ITB17-042D: INFINITI; DTC P0456 CAUSED BY EVAP LEAK AT VENT CONTROL VALVE O-RING
• ITB09012F: SERVICE INFORMATION...EVAP leak DTCs...a loose fuel fill cap may be the cause.

Platform-Specific Known Issues

• Infiniti Technical Service Bulletin ITB17-042E specifically calls out the EVAP vent control valve O-ring as a common cause for P0456 on the 2010 M45. [Bulletin #ITB17-042E]
• TSB ITB17-042D notes the same issue for the 2009 M45, but revises the repair procedure to replace the entire vent control valve assembly, as the O-ring was discontinued as a separate service part. [Bulletin #ITB17-042D]
• TSB ITB09012F reminds technicians that a loose fuel fill cap is a primary cause for P0456 and should be checked first. [Bulletin #ITB09012F]

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure (FTP) Sensor Voltage — expected: 1.3V to 1.7V with key on, engine off (KOEO) at normal atmospheric pressure.. Failure: A reading stuck near 0V or 5V, or a value that doesn't change when pressure is applied/released, indicates a faulty sensor or wiring issue.
• EVAP Purge or Vent Valve Solenoid Resistance — expected: Approximately 20 to 30 ohms when measured across the two electrical terminals.. Failure: A reading of infinite resistance (open circuit) or very low resistance (short circuit) indicates the solenoid coil is bad and the valve needs to be replaced.
• FTP Sensor Connector Voltage — expected: With the connector unplugged and KOEO, one pin should have a 5V reference from the ECM, and another should have a good ground.. Failure: Absence of the 5V reference or a poor ground points to a wiring problem between the sensor and the ECM, not a faulty sensor.

Scan Tool Commands That Help

• Infiniti CONSULT-III plus: EVAP System Leak Check (Active Test) — This is the manufacturer-specified procedure for diagnosing a P0456. The command manually closes the EVAP vent control valve, sealing the system. A technician can then apply low pressure with a tool (like the J-42909) and monitor for pressure decay to confirm a leak without a smoke machine.

Wiring & Ground Locations

• EVAP Vent Control Valve — Attached to the EVAP (charcoal) canister, located at the rear of the vehicle on the passenger side, above the suspension components.. This is the location of the most common leak source for P0456 on this vehicle, as identified by multiple TSBs.
• EVAP Canister Purge Volume Control Solenoid Valve — In the engine bay, on the right (passenger) side of the engine compartment.. A faulty purge valve that is stuck slightly open will cause a leak path to the engine intake, triggering a P0456. Its location is needed for testing and replacement.
• IPDM E/R (Intelligent Power Distribution Module Engine Room) — Located at the right rear of the engine compartment.. This module contains fuses and relays that power components of the EVAP system. A fault here could cause electrical issues with the valves.
• BCM (Body Control Module) — Behind the glove box.. The BCM communicates with other modules regarding vehicle status and can be involved in the diagnostic logic for some emissions-related warnings.

Real Owner Repair Stories

• YouTube channel 'Trust Me I'm an Idiot' (2006-2010 Infiniti M35x (same platform and EVAP system as M45)) — Check Engine Light with EVAP code P0447 (Vent Control Circuit Malfunction), which is often related to P0456 issues.
  ❌ Tried (didn't work) Removing the EVAP vent control valve and cleaning it with electrical cleaner.
  ✅ What actually fixed it Replacing the entire EVAP vent control valve assembly (Dorman 911-503) resolved the issue. The owner confirmed that the cleaning attempt failed and a new part was required.

"I Checked Everything" — The Actual Cause

• An intermittent EVAP purge valve can pass a static smoke test but still be the cause of a P0456 code. The valve may not leak when at rest (closed), but can stick partially open after being commanded to cycle by the ECU during a drive. A more advanced diagnostic technique is to use a scan tool to cycle the purge valve multiple times while a vacuum gauge is attached; a glitch or sticking will become apparent when it fails to hold a vacuum after being commanded closed.

OEM Part Supersession History

• 14935-JF00A / B / C → 14935-JF00E — Part revision and consolidation by the manufacturer.
  Heads up: The newer part numbers are direct replacements for the older ones. Using the latest version (14935-JF00E) is recommended.
• 16618-JF00A → N/A (Discontinued for service) — Infiniti discontinued the sale of the O-ring as a separate part, now requiring the replacement of the entire vent control valve assembly per later TSBs.
  Heads up: While the part may be found from old stock, the official repair procedure no longer uses it. The updated valve assembly is the correct fix.
• 14950-EH100 / 14950-EH101 → 14950-EH10A — Part revision for the entire EVAP/charcoal canister assembly.
  Heads up: When replacing the entire canister, ensure you are using the latest part number for compatibility.

Model Year Variations Within This Range

• 2006-2010: No significant variations related to the P0456 code have been identified within this generation (Y50). The primary causes, TSBs, and repair procedures apply consistently across all model years in this range.