P0420 on the 2018 Toyota Sienna
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.
| TTT069822 | 2022-10-17. Service bulletin. TT: Some 17-22MY Highlander and 17-20MY Sienna vehicles may experience a MIL ON condition with DTC(s) P042000, and/or P043000. This issue could involve deteriorated catalyst material from the bank 1 or bank 2 catalytic converter. |
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| TTT069822 | 2022-09-15. Service bulletin. TT: Some 17-22MY Highlander and 17-20MY Sienna vehicles may experience a MIL ON condition with DTC(s) P042000, and/or P043000. This issue could involve deteriorated catalyst material from the bank 1 or bank 2 catalytic converter. |
2 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.