I just asked that question of Xantrex, The tech said don't splice the wire, run new wire with new sensor. He then explained that the temp sensor is more trouble than its worth, so I did not replace my temp sensor when I replaced my inverter.
I was just gonna use the existing wire and crimp on a new phone plug, and a new plug on the new sensor, so I could just plug them together with a phone connector. He said don't do it, so I didn't. Their help line is pretty responsive, so give them a call.