Service bulletins for the 2021 Honda Civic
A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.
79 on file from NHTSA, as of 2026-10-19.
About P0420 on the 2021 Honda Civic: what the code means, and the bulletins and recalls about the same components.
By type
By component
By trouble code
Only bulletins with trouble code: P0420 are shown. Show all
| ATI&12022024909 | 2024-12-12. Other. ENGINE. Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2024 Accord 1.5Ls, 2021-2024 Civics 1.5Ls, 2023-2024 CR-Vs 1.5Ls, and 2017 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Efficiency Below Threshold] stored. To better understand the cause of this condition, AHM would like to specific parts from the vehicle prior to you attempting a repair of any kind. |
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| ATI&11052024902 | 2024-11-14. Other. ENGINE. Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2024 Accord 1.5Ls, 2021-2024 Civics 1.5Ls, 2023-2024 CR-Vs 1.5Ls, and 2017 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Effciency Below Threshold] stored. To better understand the cause of this condition, AHM would like to specific parts from the vehicle prior to you attempting a repair of any kind. |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.