Hi, Just checked my manual and the oil warning is an oil can shape on a red light. The circle with the exclaimation mark IS the brakes... So check the level on a level surface and top up accordingly. You would also be advised to check for leaks from the brake circuit AND the brake pad depth remaining. Sounds like your pads ar a shade thin perhaps.. Des. . . ;)
Low brake/clutch fluid level or defunct sensor or sensor wire short to ground. S40 doesn't have low pad warning feature, it relies on a metal clip rubbing against the disc making a noise which annoys you each time you brake so you investigate and notice the pads need changing! Assuming clip was fitted to the pad by your last mechanic.... Pete
This noise that annoys you, what does it sound like? My front right (i think) is making a noise at the moment but its a very high pitched squeek. Why do brakes squeek? It shouldn't be that low as had it serviced only a week or so ago and they reckond there was another 5000 miles left in the pads.