P0455 on Cadillac vehicles A large leak in the evaporative emissions system — often a fuel cap left off

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 Cadillac filed with NHTSA whose summary names P0455. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• 21NA124 Service bulletin
  2021-05-25 · Electrical System
• This service bulletin provides diagnostic tips/steps on testing for possible EVAP leaks in the system to correct a customer concern of an MIL Illuminated with DTCs P0442 and/or P0455 Set.
• 21NA124 Service bulletin
  2021-05-25 · Fuel System, Gasoline — Storage — Evaporative Emissions — Canister
• This service bulletin provides diagnostic tips/steps on testing for possible EVAP leaks in the system to correct a customer concern of an MIL Illuminated with DTCs P0442 and/or P0455 Set.
• 21-NA-124 Service bulletin
  2022-12-14 · Engine And Engine Cooling
• This service bulletin provides diagnostic tips/steps on testing for possible EVAP leaks in the system to correct a customer concern of an MIL Illuminated with DTCs P0442 and/or P0455 Set.
• PIE0528 Service bulletin
  2019-07-11 · Engine And Engine Cooling
• Some customers may note a Check Engine Light related to the evaporative emission canister performance. Technicians may find the following DTCs set: • P0442 • P0455 • P0446 • P0449 • P0498 This engineering informational bulletin is requesting information from the field on warranty parts for complete canister assemblies that apply to the DTC codes specified and has leak conditions. Engineer

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