# P0420 on the 2023 Subaru WRX

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.

## Bulletins for this model year that name P0420

- [10246083](https://open.wenmarpro.com/bulletins/10246083), 2023-12-05: This Service Information Bulletin announces diagnostic service procedures to be followed when DTC P0420 \(Catalyst System Efficiency Below Threshold Bank 1\) is detected by the Engine Control Module \(ECM\).