Used my 'hidden' manufacturers fitted towbar for the first time yesterday (2015 Allroad) to tow a small trailer, the car defaulted to the parking plus screen despite only going forwards (selected off with the button) and my sat nav screen said "Insert Correct Media" despite the SD Card being inserted already and working fine prior. Once I disconnected the trailer the Sat Nav recognised the SD Card again and Parking worked as before. Any quick fixes or simple things to look at as it feels like there is some cross feed between the towbar and the parking sensors and not sure how the Sat Nav is affected as it still recognises the Satellites just not the SD Card?