hi guys, right, i've got this nigglin prob with my a4, and i've been told its caused by a faulty secondary air injection unit, and it causes the cooling fan to run all the time from turning on the ignition till i turn it off, it causes the car to run cold all the time and its as thirsty as anything!! just wonderin if anyone else has had a problem like this and whether that was found to be the fault or something else, i've also been told that there is a vauxhall unit which is exactly the same as the audi one but just a hell of a lot cheaper but the lad who told me wasnt sure of what model it came from. dont suppose there are any audi tech heads out there or someone who works in their parts departments!? any help would be great. cheers.