P0712 Error and flashing O/D off light

[Mikerson]

I dropped my van off at Les Schwab to have them help pinpoint a persistent suspension clunk (they couldn’t figure it out, more later) and when I got it back, I had the O/D light on the shifter flashing. Just got the code read. P0712 which is a temp sensor low signal error. Anybody have this before? Ideas on what could cause this besides a bad sensor?

Background on van/tranny: ~145,000 miles. 4r70W trans was rebuilt and converted to 4wd with the different output shaft about 15,000 miles ago. The trans guy insisted on installing a shift kit. “I do this in all my transmissions, you’ll like the way it shifts.” I actually hate it, but anyway…The torque converter is a new HD unit installed at the rebuild. I replaced the low quality aftermarket trans filter the shop installed with a motorcraft filter about 6000 miles ago. It is full of motorctaft Mercon V. Currently trans shifts and drives fine with no problems.