EC200 sensor fault?

Hi There

We bought an Autotrail Dakota SE 2003 in Nov 5 and have not been anywhere in it YET due to lockdown #2 and #3. I have been slowly going through the hab area, rectifying small issues. One I have noticed is the EC200 digital control panel (Sargant) shows the outside temperature is -29.3 degrees C. Inside temp seems to be recorded correctly. Now it has been chilly of late but not THAT cold!!! I have rebooted/reset the unit as per the EC200 manual from Sargant but no joy. Is it likely to be the probe/sensor?  I have no idea where to find that! or is it likely to be the control panel itself? I see Sargeant sell new probes/sensors for £15 which according to one review will fit the EC200 but not made specifically for it. Thanks for any replies/advice wiser heads out there in MH land may have.

Paul