Hi guys, hope someone here can help me.

I've had a 2005 A3 for 3 1/2 years, and not long after I bought the car the emission warning light came on the dashboard. I took it to a local garage who did a diagnostic check and said it was just a faulty sensor in the exhaust system, and cleared the light. However about a month later the light came back. As it made no difference to how the car behaved I ignored it.

Then I had it serviced about 2 years ago and it came up that the Catalytic Converter had gone (£600 later it was replaced and the light had gone) But again, a month later it came back. Numerous services and checks later and I always get the same response (faulty sensor)

Then, last night, driving at about 50mph and the car starts juddering fairly noticeably, and the emission warning light starts flashing?! I pull over and look in the owners manual for any clues as to what it might be but nothing. I manage to nurse the car the last two miles home and park it up on the drive. I had a listen to the engine and there is an intermittent whirring that wasnt there before.

Does anyone have any idea what it might be? Will the car even be ok to drive to a garage to get it looked at?