electronic Load Detector Help

[1PhatCX]

i'm throwin a Code 20 on my ECU in my 89 Civic CX Hatch and need to know how to fix it exactly. i know its on the inner fender but dunno what exactly, someone suggested cleaning the surface where it touches the inner fender and i tried that, reset the ECU and still gettin that code. so now i need other ideas too, also what would cause this?? thanx for all the help

this is the ELD Right? that little box that has a single bolt going through it into the inner fender?