R31 Tecma head false full reading

I am 2 weeks into the loop on 2023 R31CB. Main head gives red "full" light after one day out. Did the reset several times. Tank nearly empty, viewing rank with bright light shows no debris. Changed to green for 6 days. Now reading full again. Pumped out yesterday. No debris. Cut one wire to high sensor. Reset. No change. Cut second wire to sensor, reset, no change. Joined the two wires essentially jumping past the sensor, reset, no change. I can only do emergency flush. How can I fix this for the months ahead on this voyage?

No one else having this problem?
I called Thetford yesterday. Sadly, they have eliminated ALL human technical support and all I got was a useless AI chat bot and zero assistance. Hoping someone here can offer an idea. Thanks.

Sounds like an intermittant short?

We have had similar issue. One area to check is make sure there is no tape holding the sensors in place. The tape causes false readings. The other thing I did was added a squirt of dawn dish soap, then filled the tank with clean water and pumped out. It took doing this twice to get the green indicator. I listened for when the tank was getting full similar sound to when the water tank is full.

This from goodle search. Alternative Solutions: If the sensor fails, a 620 ohm resistor can be used to bypass the sensor and make the red light turn off, a commonly suggested fix in the Reddit/GoRVing community.
Seems like cutting both wires like you did though would be similar so not sure this is a good suggestions.

Try disconnecting or removing the sensors from the tank all together. My sensors fell of the tank years ago. Always shows green. We just remember to pump out every 4-5 day or when we get fuel. Never an issue for 7 years.

Maggie Anne said:

This from goodle search. Alternative Solutions: If the sensor fails, a 620 ohm resistor can be used to bypass the sensor and make the red light turn off, a commonly suggested fix in the Reddit/GoRVing community.
Seems like cutting both wires like you did though would be similar so not sure this is a good suggestions.

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Put the resistor across the two wires.

We have the same issue and I just want to bypass but cutting one wire, both wires, and wiring together still shows red. Presumably we need a resistor but what type?

shontm said:

We have the same issue and I just want to bypass but cutting one wire, both wires, and wiring together still shows red. Presumably we need a resistor but what type?

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Get a multi-pack. Pick one and test it. If it works and doesn't get hot after awhile, you're probably ok.

Had the same symptoms on both our R-29 and our R-31. The most common cause was some sticky $hit and toilet paper that clings to the inside wall of the holding tank. It stays there after a pump out sometimes. Every once in a while, you need to fill the tank with some water and Dawn dish detergent - or the product that Thetford makes for this. Leave it in for a while and even take the boat out for a spin to get some sloshing. Then pump and rinse a few times.

The other problem that we had on the R-29, was that the only things keeping the holding tank in place, were gravity and luck. Sometimes in rough seas, the tank would shift toward the starboard side and allow the sensor to get too close to the air conditioner return and it would give a false reading. I made some cleats to hold the tank in one spot and eliminated that problem.