Easy Q....I just cant find the answer in my owners manual....what are the little digital numbers that appear on the dash?
At start up, mine reads #1...then goes to 5 or 6 while driving. Also, the lower right corner seems as if the little blackend squares have formed a triangle....old age? Thanks.

BTW..just swapped my 02 sensor with the Ford Mustang part at Autozone....thing was on so tight, I broke their loaner tool. It eventually came off, I spliced the new one in, and now better gas mileage.