General LSX Automobile Discussion - Issue with coolant temp gauge

Im having an issue with my coolant temp gauge after my header install. When moving the alternator to do my motor mounts i accidentally broke the plastic plug on the sending unit. I replaced the sending unit, and the gauge seemed to be stuck at 210. Im sure i have the right sending unit, i unplugged it and the gauge dropped to zero. Then i plugged it back in and now every time i start the car it goes to about 150 for a second then drops to zero, and the fans kick on immediately. Any ideas?

sounds like its kicking into defult mode. which will richen up the mix and cause the fans to kick on. check all your wiring and connections to see if you have a break or if a wire is laying on the headers.

I know its probably throwing a code because of the rear 02 sensors not being connected. Could that cause the fans to come on?

No...they only monitor cat efficiency