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P1456

Evaporative Emission Control System Leak Detected Fuel Tank System.

  • Infiniti
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
56
FaultThe specific fault in that area

What it means

On Infiniti, P1456 means the engine control unit has detected a leak in the evaporative emission control system around the fuel tank side, meaning the tank, filler neck, cap and associated pipework. The leak test usually runs after a cold soak with the fuel level in a set range. The system is sealed and the pressure or vacuum change is monitored. If the sealed system fails to hold, the code is stored and the warning light comes on.

Symptoms

  • Engine warning light on
  • Faint fuel smell around the rear of the car or near the filler
  • Fuel filler cap found loose, damaged or missing its seal
  • Hissing when the fuel cap is opened, or the cap is hard to remove
  • Difficulty refuelling, with the pump nozzle clicking off repeatedly
  • No noticeable change in how the car drives

Possible causes

  • Fuel filler cap loose, worn, damaged or the wrong typelikely
  • Cracked or perished filler neck, filler hose or breather hoselikely
  • Leaking EVAP vent control valve, or a vent line that is damaged or restrictedpossible
  • Faulty or leaking fuel tank pressure sensor, or a damaged sensor connectorpossible
  • Corroded or leaking fuel tank, tank seal or fuel pump or sender flange sealpossible
  • Leaking EVAP canister or canister purge line connectionrare

How to diagnose

  1. Read the stored codes and freeze frame data, noting fuel level and temperature when the fault set, and check for other EVAP codes.
  2. Check the fuel filler cap for correct fit, a damaged seal or cracks, and make sure it clicks tight.
  3. Visually inspect the filler neck, breather hoses, EVAP pipes and connectors for cracks, splits, loose clips and corrosion, including underneath the car.
  4. Inspect the wiring and connectors of the fuel tank pressure sensor and EVAP vent control valve for damage, water ingress or corrosion.
  5. Use the scan tool's live data to check the tank pressure sensor reading against known atmospheric pressure with the system vented.
  6. Activate the EVAP vent control valve and purge valve with bi-directional tests, listening and checking that they operate and seal correctly. Test procedures vary by model and year.
  7. Carry out a smoke test of the EVAP system at low pressure to find the leak, following the manufacturer's procedure for your model.
  8. Clear the code after repair and run the EVAP monitor drive cycle to confirm the fix.

How to fix

  • Fit a correct, good-quality fuel filler cap and replace it if the seal is damaged.
  • Replace the cracked or perished filler neck, hoses or EVAP pipes, and refit the clips securely.
  • Replace the leaking or sticking EVAP vent control valve.
  • Replace the faulty fuel tank pressure sensor, or repair the wiring and connector.
  • Replace the leaking fuel pump flange seal, tank seal or damaged tank as required, then confirm the system holds pressure.

Can I keep driving?

Low severity

The car is safe to keep driving, so book it in for repair soon. Check the cap first, and if you smell strong fuel or see liquid fuel leaking, stop and get it checked straight away.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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