From information on various online posts and considering the fault message stated "you can continue driving" I assumed that there would be no risk of a serious brake failure and that if the part were indeed faulty then the message would soon reappear. As it turned out that is exactly what happened the following day. On having it diagnosed by the local Audi service agent they confirmed that the brake pressure sensor should be replaced at a quoted cost of $847.95!!! (GBP425). Having previous experience of overpricing for european car parts (major NZ parts supplier quoted $250 for a drive belt for a VW V5 golf which I ended up importing from a UK supplier ,same brand and part number total cost including freight $35!) I searched for the part number and found it widely available from various sources such as ebay, amazon and ali express. Prices varied but images all showed identical markings to the original part. A little research on brake booster pressure sensors in general revealed that these parts are normally expected to last the life of the vehicle. The fact that this particular VW sensor is so widely available from a variety of sources strongly suggests that it is indeed a part that is prone to fail well before it's life expectancy. I purchased a replacement sensor for the A5 from ali express. Time to fit - under 2 minutes. Total cost of part including freight- $15 . I have since seen the same part online for as little as US$5.99. Have Audi been using a very cheaply produced and inherently unreliable part that could lead to costly repairs to the ABS system? If so there should be a recall on all cars fitted with this part and a reliable replacement should be fitted free of charge. Regarding any warranty period- here in New Zealand we have the consumer guarantees act which basically states that anything you buy should be expected to last a reasonable time regardless of the manufacturers warranty period . For example if your appliance with a 1 year warranty fails after 18 months and the normal life expectancy of that type of appliance is 2-3 years then it must be repaired or replaced free of charge. I'm pretty sure the same applies to car parts.