4 wire Oxygen (Lambda) sensor for MX5 & Eunos Roadster mk1 & mk2, 1994 on. Can also be fitted to earlier models with a bit of re-wiring.
This is an aftermarket replacement and so the wires will need joining on to the Mazda plug from the old sensor
Original Mazda part has wiring as follows:
Signal wire is blue (connect to black on new sensor)
Heater wires (x2) are black (connect to white wires on new sensor)
Ground wire is white (connect to grey on new sensor)
NM00241.