what is the e=cat button on the instrument panel?
catalic converter-if light is on you may need a new cat converter.
First off, sorry, could be a bummer of a problem to fix. I recommend checking out Autozone to see if they have a code reader for your OBD-1 Mazda. It may work with a Ford code reader. If not, I would try to find a website with Diagnostic instructions, typically there is a Diagnostic Port that you can use to check codes. The catalytic converter is an emissions piece located in your exhaust, looks somewhat like a small muffler, and is usually just downstream of the engine. That is the piece that most likely needs replacement. Good luck.
Search Mazda MX-6 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mazda MX-6 Experts