Citroen C4 Picasso - 1.6 THP engine - albapa

I know there have been a lot of problems with the Citroen/Peugeot/BMW/Mini 1.6 THP petrol engine: chain tensioner, (turbo?) and carbon deposits. Is there a safe date after which they can be considered reliable? In particular, I'm looking at a 2013 C4 Picasso with 1.6 THP - worth buying or better to avoid? Thanks!