Amazing! My Overheat Exh Sys lite came on - I was investigating tearing apart the interior looking for the sensor when I found this post. It was a blown fuse near the Emission Control Unit. I did not even see the fuse on the wiring diagram. Thanks 2GSLSE!

I just ran into this exact problem!!!! Just started up my 85 rx7 and that light comes rite on, where is this fuse??
https://cimg4.ibsrv.net/gimg/www.rx7...0feed0dd1.jpeg
I have both these lights on, and none of my gauges work along with some other problems I need to attend too lmao

You don't say what you have for an engine 12A or 13B, but here's some info:

https://www.reddit.com/r/RX7/comment...my_fb_control/

heat hazard fuse
 

It's been a long time but I think this is the fuse. It's right next to the ECU and hood latch pull. You may have other issues though.

https://cimg3.ibsrv.net/gimg/www.rx7...6c7ac141e2.jpg