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P1456

Evaporative Emission Control System Leak Detected Fuel Tank System.

  • Honda
  • 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 Honda, P1456 means the evaporative emission (EVAP) control system has detected a leak in the fuel tank side of the system. During the ECU's leak monitor, the system could not hold or build the expected vacuum or pressure, or the pressure change was outside the expected range. This is a leak-related fault, not a fuel tank temperature sensor fault.

Symptoms

  • Malfunction indicator lamp on
  • Fuel smell around the rear of the car or near the filler
  • No obvious change in driveability in most cases
  • Fuel filler cap found loose or damaged
  • Failed emissions test due to EVAP readiness not completing

Possible causes

  • Fuel filler cap loose, missing, wrong type or with a worn seallikely
  • Perished or cracked EVAP hoses and pipes between the tank, canister and purge valvelikely
  • Leaking fuel filler neck, seal or tank-mounted connectionspossible
  • Faulty EVAP canister vent shut valve or purge control valve sticking openpossible
  • Fuel tank pressure sensor fault or wiring problem giving false readingspossible
  • Damaged or corroded EVAP canister or fuel tankrare

How to diagnose

  1. Read stored codes and freeze frame data, noting fuel level and conditions when the code set
  2. Check the fuel filler cap is fitted, tightened until it clicks, undamaged and has an intact seal
  3. Visually inspect the filler neck, EVAP hoses, pipes and connectors for cracks, splits, disconnection or fuel staining
  4. Inspect the wiring and connectors of the vent shut valve, purge valve and tank pressure sensor for damage and corrosion
  5. Use a scan tool to check the fuel tank pressure sensor reading with the system open to atmosphere and compare it with the manufacturer's specification
  6. Operate the vent and purge valves from the scan tool and listen and feel for correct operation, checking they seal when closed
  7. Smoke test the EVAP system at the manufacturer's specified low pressure to locate the leak
  8. Follow the model-specific Honda EVAP test procedure, as layout and test steps vary between models and years

How to fix

  • Replace the fuel filler cap with the correct type if it is faulty or does not seal
  • Replace cracked, perished or disconnected EVAP hoses, pipes or clips
  • Repair or replace the filler neck, seals or tank connections found leaking
  • Replace a faulty vent shut valve or purge valve
  • Replace the fuel tank pressure sensor or repair its wiring if testing shows a fault
  • Replace a damaged EVAP canister or fuel tank, then clear the code and confirm the monitor completes

Can I keep driving?

Low severity

The car is normally safe to drive and this fault rarely affects performance. Book it in soon, as a fuel leak smell should be checked promptly and the car may fail an emissions test.

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

This code for other makes

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