Dan k

Hi, I’m hoping somebody could help. I brought an A6 2008 plate a year ago. After 10mins of driving my ESP light comes on and says see owners manual. The car still drives fine with regards to ESP doesn’t feel any different. Also every 100 miles or so it cough/chugs and I have smoke coming from exhausts but is fine again after a few miles. It’s meant to have self cleaning DPF but it doesn’t kick in so I’m guessing that is something to do with that but no mechanics seem to know. Thanks