ATF: North Trail - Black Tank Sensor

I have used my rig 3 times now since I purchased it new. Each time I have been diligent about flushing the black tank with the "flush" system as well as using chemical tabs in it after its flushed and empty.

This last trip, I dumped completely, flushed for 10 minutes, added a few cups of water and my "blue stuff". The tank reading showed 1/3 full. I dumped again, all I got was "blue stuff" through the hose.

Is it possible the sensor has gone bad? Am I doing something wrong?

This is very common with these sensors. They are more like a guestimate guage.

If it concerns you, dump a 10# bag of crushed ice in the tank with a little Dawn dish soap, right before you hit the road. This may scrub out some of the paper that is probably stuck to the sensor.

After using your rig for a while, you will begin to know when your tanks are about full. If the black tank burps air back at you when flushing, it is most likely full.

After-market probe-type sensors, are available. Some folks have said the work more efficiently. Trace

Erratic black tank sensor readings are common across the RV industry. I've had good results with using a down-the-toilet flush wand. I'm lucky in that I can dump at home and take my time rinsing the tanks.

Another possibility is that the drain tube inside the tank is uphill and you aren't getting all the stuff out. When on the road, I can dump & flush before leaving a campground, and when we get to the next campground if I hook up so I can dump, there will always be some stuff coming out. Kind of like the plumber's old saying "$h&# don't run uphill".