Trying to recalibrate my TMP.
When I get to -250 cal I keep getting an operator error prompt. Any ideas why?

If your doing it by the book and still getting the oper error it's a software glitch. Cut the machine off and reboot. It should let you calibrate then. This is true if your talking about a K anyway.

What kind of machine? Make sure your transducer connected to the meter is dry. If you don't have one there you may have gotten the inside of the meter wet. Make sure your lines are full with no air. I suppose there could be other problems but not sure what off hand.

K Machine, doing everything by the book, all lines dry. Will reboot.

Same thing has happened to me. Sometimes caused by wet transducer or a kinked line. But sometimes I think it's caused by pulling the pressure to 250 too fast. I just get out of that calibration mode, get back in and go slow on drawing with the syringe and it works fine.

I just had this happen to me. Thought maybe it did not switch to -250 page when I hit confirm.. I just went back to options and started over. No Worries!

I have had the same problem when I was to slow in getting the -250, Reboot and start again!!!