P0456 on Acura vehicles A very small leak in the evaporative emissions system

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns Acura filed with NHTSA whose summary names P0456. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• BTS170202 Service bulletin
  2017-02-21 · Fuel System, Gasoline
• TECHLINE SUMMARY ARTICLE - IF THERE’S AN EVAP SYSTEM LEAK FROM THE FILLER NECK (DTC P0455 [EVAP SYSTEM LARGE LEAK DETECTED] OR P0456 [EVAP SYSTEM VERY SMALL LEAK DETECTED] IS SET), DON’T REPLACE THE FUEL FILL PIPE! INSTEAD, REPLACE THE MIS-FUEL INHIBIT DEVICE AND THE MAIN FLAP UNIT. ACURA PARTS STOCK CARRIES REPLACEMENT PARTS JUST FOR THIS PURPOSE.
• BTS170202 Service bulletin
  2017-06-23 · Fuel System, Gasoline
• Tech line summary article - If there's an EVAP system leak from the filler neck (DTC P0455 [EVAP system large leak detected] or P0456 [EVAP system very small leak detected] is set), don't replace the fuel fill pipe! Instead, replace the mis-fuel inhibit device and the main flap unit. Acura parts stock carries replacement parts just for this purpose.
• BTS170202 Service bulletin
  2017-10-18 · Fuel System, Gasoline — Storage — Tank Assembly — Filler Pipe And Cap
• Tech line summary article - If there?s an EVAP system leak from the filler neck (DTC P0455 [EVAP system large leak detected] or P0456 [EVAP system very small leak detected] is set), don?t replace the fuel fill pipe! Instead, replace the mis-fuel inhibit device and the main flap unit. Acura parts stock carries replacement parts just for this purpose.
• BEBM09252026901 Other
  2026-09-25 · Fuel/Propulsion System
• Dealer Message - The fuel fill pipe assembly may not have been manufactured to specification. As a result, small contamination particles inside the fuel fill neck may prevent the primary shut-off valve flap seal from sealing, resulting in fuel smell from the fuel fill neck area and may cause DTC P0455 or P0456 (EVAP system leak detected) to be set.
• B26-023 Service bulletin
  2026-09-25 · Fuel/Propulsion System
• Service Bulletin - The factory fuel fill pipe assembly may not have been manufactured to specification. As a result, small contamination particles inside the fuel fill neck may prevent the primary shut-off valve flap seal from sealing properly. This may result in a fuel smell from the fuel fill neck area and may cause DTC P0455 or P0456 (EVAP system leak detected) to be set.
• B26-025 Service bulletin
  2026-09-25 · Fuel/Propulsion System
• Service Bulletin - The factory fuel fill pipe assembly may not have been manufactured to specification. As a result, small contamination particles inside the fuel fill neck may prevent the primary shut-off valve flap seal from sealing properly. This may result in a fuel smell from the fuel fill neck area and may cause DTC P0455 or P0456 (EVAP system leak detected) to be set.

A stored code names the test that failed, never the part that caused it. The record above is what Acura and its owners have filed about it; the code’s page across every make has the whole file.