Nudgermanning

Anyone have any ideas why my power steering would fail for nearly a week then suddenly reappear without showing any fault codes or lights. The car is a 2016 q5 2.0tdi and the warranty is very nearly up so I'd like to get it sorted if I can. Thanks in advance 

Many thanks for your help Steve. Managed to resolve it by having a fiddle underneath the passenger seat then using obd11 to clear it. Thankfully no unnecessary costs before the mot in January 

Spent the afternoon cleaning the s3 and when jumping into the car to turn her around the warning light came on for the passenger airbag. The car was perfectly fine yesterday and the only thing I've done since is pressure wash it. Could this cause a sensor issue and is it worth waiting to see if the code clears itself. The car is a cat n but the first time ive had this fault. Any ideas guys? 

Afternoon one and all. As you can tell from the title, im both new to this forum and also new to Audi itself. Looking forward to engaging with other members during my ownership of this car and possibly future cars