Thanks Darren.

I don't have any problem with IDS navigation to be honest, & you can be sure that I tried that method. I also expected the PCM calibration update, to overwrite any previous data, but the 688 mb figure remained after the process completed (the baro sensor was unplugged too!).

The only method that actually seems to reset the Baro value to a sensible figure, is the battery disconnection method. I thought it was you who suggested it in the previous replies.

As a side note. I found it slightly odd on this age vehicle that the main menu in IDS doesn't have the "self test" option. Without this I was left wondering how I could access the CMDTC's (constantly monitored diagnostic trouble codes). Of course I found another way, but it’s hidden in the background.

Cheers for taking the time.

Dave