keep a log of mileage on my tow vehicle. Said tow vehicle. 99 percent of miles are towing the 5ver. Never been in the snow. write all towing miles in red and then a second section in green for driving miles. I figure then plus otr minus 5 percent Just a little math here.
last year in the high heat I started to get false reading of 3/4 full.
Flushed tank out with the Hydro flow fitting on the dump hose. It is a right angle with a hose water hose attachment. Then added the enzyme solution for the black water. Filled it with a third tank of water and drove 5 hours to the next campground and dumped. No more problem.
The sensors get coated and give the false reading. Try this before you drill holes or try to remove sensors.