So far as MX5's are concerned. ECU's are computers and they output control data and store fault codes (which is the real issue) as numbers. A number like 08 or 24 is the same in japanese as in english. Roadster ecu's are just the same as UK spec ones (there is some debate about the actual control values - and I would very much like to know if anyone has read the maps by connecting both to a computer, to do a comparison) and using and interrogating them is the same for both. AFAIK, they are interchangeable - but there are variations year to year and 1.6 / 1.8 / (later) 1.6 / Mk2 1.8 / Mk2 1.6 (11/99)

The Mazda UK propaganda is that it is not possible to interrogate Roadster ecu fault codes with UK diagnostic equipment. Not Mazda UK policy perhaps, or Mazda dealers are directed not to read them - but technically there is no problem. (11/99)