Why is my transmitter returning data that makes no sense?

If you've wired your sensor yourself, you've most likely connected the wires to the wrong terminals. Consult the datasheet and check carefully that you've followed the connection diagram.

If you disconnected the probe by pulling on the probe wire rather than the connector itself, you may have lost contact between one of the wires and its terminal block. Open the connector and check that all wires are connected.