[BadmanRick]

I have a 2011 Bullet Premier 19fbpr. I had the same problem. Black tank and gray tanks not reading correctly. I spent money at the dealer having them change the sensors. Within 6 months they were bad again. The problem with the original CHEAP sensors is that they are round flat surfaces and debris from the tanks coat the sensors and short them out. Therefore the full reading all the time.
I purchased the following and replaced the original sensors : For the black tank, Valterra T21301VP Horst Miracle Probe - Black Water Tanks, Pack of 4
For the gray water and fresh water tanks, Valterra T21302VP Horst Miracle Probe - Gray Water Tanks, Pack of 4
I have not had any problem since I changed to these sensors. These are available on line and at your better rv dealers.