# P0420 on the 1999 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.

## Bulletins for this model year that name P0420

- [606212](https://open.wenmarpro.com/bulletins/606212), 1999-08-12: REVISED INFORMATION TO ASSIST IN THE DIAGNOSIS OF DIAGNOSTIC TROUBLE CODE P0420 INDICATING A POSSIBLE CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD CONDITION. \*TT
- [605187](https://open.wenmarpro.com/bulletins/605187), 1999-06-03: BRIEF INFORMATION REGARDING DIAGNOSTIC TROUBLE CODE P0420 INDICATING A POSSIBLE CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD CONDITION. \*TT
- [604746](https://open.wenmarpro.com/bulletins/604746), 1999-05-11: SOME VEHICLES MAY EXHIBIT DIAGNOSTIC TROUBLE CODE P0420 INDICATING A POSSIBLE CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD CONDITION. \*TT