Read my truck is in Limp mode?

My 2010 f150 stx 4.6l vin w is in Limp mode…when I turn the truck on the transmission fluid temp gauge doesn't move. I recently replaced all coils and valve cover seal. Then my cats were cut out. Bought new and installed them with new o2 sensors that plug into cats but not the 2 that are above them. I'm guessing it's a bad sensor for trans temp. Not a mechanic but I work on my truck if I know what is wrong. Also my radiator fans fun on high constant as soon as I start it and don't shut off.