Hi everyone I am new to the forum but have owned my S3 for 4 months now. I have just had an mot done on it and it failed on emissions. I have had it plugged into the computer at the garage where it failed and there is no logged fault codes. I have serviced the car with new plugs, filters, oil and also a fuel cleaning liquid. I have taken the car on some long runs to see if that would clear it. I took the car back to the garage for an emissions test and again it failed on fast idle with too much CO2 but was ok on tick over Does anyone have any clues as to what I can check before having to get the garage to look at it. Any help would be much appreciated ?