Briefly press both the "Off" & "Footwell" buttons & release, Press "Auto" button & release!
the system will run a self diagnostic - testing all segments of the display & Flap motors! Once the motors fall silent & display freezes! Press the "Defrost" button to reset the system, delete error codes from memory & exit diag mode! wait til the system again falls silent before running up to temperature & testing system. All of this takes around a minute to complete.