Just had the same message appear on my 66 plate A4 2.0TDI.
Called local Audi garage, can't fit me in until Monday.
Read the forum and then called their parts team who told me that there is no stock of that sensor in the UK and there is a 6 to 10 day lead time on getting the part. Waiting for a call back as I don't want to run into the ABS issue by carrying on driving it (I do about 30 miles a day round trip to work and back).
Seems like this is a major part failure across the range, so hard to believe they aren't doing a recall!
