Jefrs, yes that is my understanding too. The port is used by dealers who have DOL to read fault codes more accurately than can an owner via the blinking MIL method. It is probably a proprietary port rather than a standard one like the Triumph. I wonder whether or not this method is deemed sufficient for RE to comply with the requirement that fault codes can be read (and cleared?) through the diagnostic port? Certainly I can do this and a lot more, including remapping the ECU (either by downloading a paid for dyno tested map, a free map devised by an owner or by adjusting the fuelling oneself using the software), setting tickover, balancing throttles and more on my Triumph and one can buy any number of fault code readers to suit the standard port on an OBD II equipped car, as has been the case since the mid noughties. It seems that all the Euro IV ECUs are locked and cannot be remapped by an owner.