How many of us are there? Owners of Dodge based RV's?

Do not use thread tape on the sensor. New sensors come with just enough sealant already on them, plus they have a tapered pipe thread that seals better the more you tighten it. (As long as you don't go too far.) The negative (ground) side of the circuit is through the sensor base into the block. Thread tape partially or completely insulates the electrical connection, throwing off the gauge reading.