Got into drivers seat and turned on ignition - dashboard now lit up like Christmas tree as battery change causes all manner of confusion to ECU, it now has to be coded (used #OBDEleven for this stage as its easier to get to the battery settings than #VCDS).
Coding is in 19 Gateway, Adaptation, Battery Adaptation. New Ah value entered, type changed to "Fleece" for AGM (Blei-Vliesbatterie), serial number made up from date of fitting, manufacturer "TU3" for #Exide (as its an aftermarket battery without BEM code, any 10 digit number will do)
Steering recalibrated by turning wheel to full left lock then full right lock, many other temporary fault codes had to be cleared off (all normal after battery replacement)
