HI ALL IVE GOT A SUBARU 1995 IMPORT STI AND WANT TO PUT A AFR GAUGE IN IT, WHEN I BROUGHT THE CAR THERE WAS A GAUGE IN THE BOOT AND I HAVE PUT IT IN BUT I DONT KNOW WHERE THE SIGNAL WIRE GOES TO IT GOT A 3 WIRE 02 SENSOR CAN ANY ON TELL ME WHERE IT GOES TO MANY THANKS DAVE

 

there is two but the one you need is pre turbo and the signal wire is blue but test just in case
one -pos
one neg
one -reading 0 to 5v(should kepp going up and down)
to be fair you don't need a afr in a scooby, oil temp/press is a must