With the car cold, and you key on the system. What does afr read? Don't start it, just key on.
Should start at 14.7 then climb to 20.1 and stay there..
A bad sensor will just stay at 14.7
Mine stays at 14.7, but responds quickly when started. I wonder if the Fitech ecu doesn't send voltage until it sees an rpm signal. I'll msg them and ask if this is normal, hate to replace for no reason.