P0420 on the 2017 Acura TLX
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
Nobody has written a description of this code yet.
| B19-049 | 2019-08-20. Service bulletin. Service Bulletin - The MIL comes on with DTC P0420 (rear bank catalyst system efficiency below threshold [bank 1]). |
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| BPaS01022019906 | 2019-02-10. Service bulletin. Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind. |
| BPaS11272018901 | 2018-12-07. Service bulletin. Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind. |
| BPaS11262018905 | 2018-12-07. Service bulletin. Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind. |
| BPaS11052018904 | 2018-12-03. Service bulletin. Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind. |
| BPaS10172018906 | 2018-10-29. Service bulletin. Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect the vehicle prior to you attempting a repair of any kind. |
6 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.