I got a brand new Leon FR ST (MY16) a couple of weeks ago (184PS Diesel), and about a week after I got it, it developed a fault with the start/stop system. When I get to traffic lights and take my foot off the clutch, the start/stop tries to activate and then the engine immediately comes on again, the MFD says "Start/Stop system error", and the glow plug light flashes for the rest of the journey (or until the engine is restarted). Additionally, the emissions warning light has come on and is now permanently lit up on the dash (maybe this was remotely activated by the factory in response to the emissions scandal ). I'm guessing the latter is and exhaust sensor issue (had a lambda sensor go on an old Polo, and the same light came on). Just wondering if anyone else has had issues with start/stop and what the cause is likely to be? I have got it booked in to be looked at under warranty next week, but it would be good to have some idea of what the issue might be first. Thanks! Craig. Edit: The car actually went into limp home mode the other day. I called out SEAT Assist, and they were brilliant. The mechanic found the cause of the problem - the seal around the turbo pipe had degraded (not good on a brand new car), and was preventing a flap from closing (according to the breakdown report he left with my wife). He replaced the pipe and the problem went away. He said the part would be going back to VW in Germany for investigation, as he's seen the same thing on several new cars with this engine - clearly a manufacturing defect.