From 1996 (US), Miatas are OBD-II: plug a generic scan tool into the connector under the dash near the driver's knee and read standard P-codes. No jumpering, and you also get live sensor data and freeze-frame. This covers late NA (1996-1997) and all NB and later cars.
Any cheap generic reader pulls the codes; you do not need a Mazda-specific tool for the basics.
Common, well-defined generic codes on these cars and what they usually mean her
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