Try this first
Before you swap out the sender, try something. The previous owner of my 1984 C30 complained that he had to swap out the sender almost every year, and sure enough when I took over, the guage did not work. However, after some investigation, I discovered that the sender was not at fault. Occassionally the guage itself simply sticks at E. A simple rap with the head of a screwdriver fixes it. Don't know if this will help, but it's worth a try.