Gray Valve

[djsdak]

My gray tank reading does not drop below 33%. Any ideas on how to unstick the valve so it reads correctly?

[travelingjw]

Are you sure it is the valve and not the sensor. If not, I would try two things. First, put some Dawn liquid soap in the tank (just a capful), or use a commercial sensor cleaning product, and drive around for a bit. See if this clears the sensor error. If you can't move, run your hot water into the tank along with a tank cleaner and let it sit per instructions.

[ependydad]

The sensors of all RVs are notoriously inaccurate. My guess is that the 33% is just a bad sensor than actually a problem with the tank not emptying. We tend to ignore the sensors.

[ARoamer]

X3, the OEM tank sensors for grey and black are prone to be inaccurate by design. Build up on the individual sensors give false readings. Of all RV's I have owned only the fresh water sensors has been the most reliable and trouble free.

[Foretm]

I use a 1/4 cup of Thetford Aquamax in my grey and black tank at the start of each trip and have never had an issue. If for some reason the sensors start acting up, I put a 1/2 -1 cup of Aquamax in the shower or toilet and then fill the tank up using the shower or the tank flush. I then let is sit for a few weeks and then drain the tanks and all is well again. if you have something on the sensor, the best way to clean it is to have water sit on it for a long time. Water will dissolve just about anything over time.