Did it work before or did you just install it?

I had the same issue when I installed mine except the reading was different numbers.

I unplugged the OBD2 and the sensor from the black box, waited 15 min, plugged in the egt sensor then the OBD2 port.

After that I got some new selections for the right box for EGT and it has worked flawlessly.

I had selected one that was for EGT display but it was the wrong one.