P0456 on Honda 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.

Owners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — what was said, not a finding that it was true.

Bulletins and campaigns Honda 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.

• ATI&07062021 Service bulletin
  2021-07-06 · Fuel System, Gasoline
• Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2020-2021 Odysseys with a customer complaint of fuel smell and/or MIL on with DTC P0456 (EVAP System Very Small Leak Detected) stored. To better understand the cause of this condition, AHM would like to inspect & collect specific information from the vehicle prior to you attempting a repair of any kind.
• ATI&07202021902 Service bulletin
  2021-07-20 · Fuel System, Gasoline
• Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2020-2021 Odysseys with a customer complaint of fuel smell and/or MIL on with DTC P0456 (EVAP System Very Small Leak Detected) stored. To better understand the cause of this condition, AHM would like to inspect & collect specific information from the vehicle prior to you attempting a repair of any kind.
• ATI&07222021901 Service bulletin
  2021-07-22 · Fuel System, Gasoline
• Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2020-2021 Odysseys with a customer complaint of fuel smell and/or MIL on with DTC P0456 (EVAP System Very Small Leak Detected) stored. To better understand the cause of this condition, AHM would like to inspect & collect specific information from the vehicle prior to you attempting a repair of any kind.
• ATS170206 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. HONDA PARTS STOCK CARRIES REPLACEMENT PARTS JUST FOR THIS PURPOSE.
• ATS170206 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. Honda parts stock carries replacement parts just for this purpose.
• ATS170206 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. Honda parts stock carries replacement parts just for this purpose.

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