As said, the 'emission control system' light has come on recently. I think its due to replacing the rear lights. The car doesnt feel different to drive at all and doesn't make any strange noises..
I think its due to replacing the rear lights which i did a last weekend. A guy at my local MOT garage said that Audis often have these problems when the circuit is broken.
He suggested i removed my battery for 5mins and then plug it back in.
Before i do anything, someone must have come across this problem before. anyone help?