Originally Posted by first5thwheel
My sensor reads correctly for the grey, but even empty my black water always reads 1/3 full. I have flushed it and flushed it to the point of clear water and it never reads empty. Is it a big job to replace the sensor? the 2/3 and full work fine but it always glows read for the 1/3 ????
I've never replaced a sensor but, most would depend on how easy your access was to it. On my old rig, I had easy access to the tank and sensors, so I'll guess 30 mins.
My present rig, the tanks are enclosed in the basement with only small access panels. So I would check your access first.
It's still possible your sensor it good. If you have the time and patiences, fill it with clear warm water and a lot of strong detergent. Wait for a few days and flush good. This won't really cost anything and then you'll know for sure.