I have two codes that I cant find the problems or solutions for.

The code displayed on my mini cooper dashboard is CC-ID 031 so I took the car to auto zone and they found code p115c but were unable to tell me anything about it for reasons I do not know. I have been looking for a cause and solution for this but I have had no luck. My car was in the shop for 5 weeks for extended warranty purposes but they replace the water pump head gasket and a cylinder head and a temperature gage. I got the car around lunch time and drove it to work on my way home from work is when the codes came on and I can hear a hissing noise from the engine and cannot find where it is coming from. My shop is new to working on minis and they are the only ones I trust I have been using them for almost 5 years. And I just got the used car about 6 months ago and we are looking at ways to fix it up. Any help would be appreciated.