Knock sensor..........ebay.
 

I found one that looks right and the seller said no codes from it. At $9.00 I can't go too wrong, but he said the numbers stamped on the side was 76 816. I have 2 of them on is 76 762 and the other is 76 712. They both look the same and both give the knock sensor code. The wiring is good from the ECU to the sensor, well it has continuity at least. If I reset, the light comes back on after I rev it after a minute or so.

What do you think? The part comes off a turbo, doesn't say year and mine is an 87 N/A, but I would think a knock sensor is a knock sensor on these, just detecting if there is detonation and adjusting accordingly.

Thanks
Russ