P0421 on the 1996 Mazda 626
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.
| 00598 | 1999-03-16. Service bulletin. SUBJECT REGARDING MALFUNCTION INDICATOR LIGHT (MIL) ILLUMINATION W/DTC P0421. *YC |
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| 00598 | 1999-03-11. Service bulletin. SUBJECT REGARDING MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATION WITH DTC P0421. *YC |
| 00598 | 1999-02-03. Service bulletin. SOME VEHICLES MAY EXHIBIT A MALFUNCTION INDICATOR LIGHT (MIL) ILLUMINATED WITH DIAGNOSTIC TROUBLE CODE (DTC) P0421 STORED. *YC |
3 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.