I have a fault come up, saying that the Heater element for the auxiliary heater is faulty or not working. (00361). Excuse my ignorance, but does anybody know where this is located, and is it an easy/expensive job to fix if I do it myself? I was going to try it this weekend, along with some other issues with he car! (2006 A3 2.0 170 TDI) Thanks for any help!