On the first service from new on my Plus 4 (back in 2016) a factory flash upgrade was carried out (or installed - not sure what the correct term is) on (or to) the ECU. I'm just about to replace the vehicle battery and remembered reading somewhere (probably in Dave Welling's book) that disconnecting the battery can return the ECU to its factory settings. Does anyone know if this wipes out the flash upgrade or just the data it's gathered since the upgrade was carried out? Thanks.
