Thanks overlander63.
Problem solved! I turns out the gain WAS set all the way off! Now I have to reset to sweet spot.
Very weird since I am the only driver and to be honest over the coarse of 16 years I've probably checked settings 3 times. If the 0 volts wasn't displayed on the front, I may never have known about this.
Maybe when I went in for either an old change or emission test, someone "accidentally" moved something. Our last trip out early May everything was ok.