# P0420 on the 1998 Mazda Millenia

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

- [620007](https://open.wenmarpro.com/bulletins/620007), 2001-07-09: SOME VEHICLES MAY EXHIBIT MALFUNCTION INDICATOR LAMP ILLUMINATION WITH DIAGNOSTIC TROUBLE CODE \(DTC\) P0420 / 0421 OR P0430 / 0431 STORED IN MEMORY WITH NO DRIVEABILITY CONCERNS PRESENT. THIS CONDITION MAY BE CAUSED BY AN OVERLY SENSITIVE REAR OXYGEN SENSOR\(S\), WHICH FASELY INDICATES AN EMISSIONS CONCERN AND A DTC TO BE STORED. \*TT