after updating D180 to 5.1.1 did DSAB and got msg no OAT found. did DSAB again and watched OAT count down from 175 to what would be normal temp then go to not available. OAT is connected to EFIS and was working in past.
Check and make sure that there's no OAT selected on any of the GP inputs on the EMS side of things. This isn't toggled during a firmware update, so what you're seeing is a little weird. Also confirm that under the EFSI setup menu that you have type 2 selected. Does your mag heading work, by the way? If that had gone away, that would inhibit the display of the OAT too.
again and watched OAT count down from 175 to what would be normal temp then go to not available. OAT is connected to EFIS and was working in past.