As above really but the most common are crank pulley/aux belt tensioner they cause knocking on idle then there's the egr valves /injectors /dmf's and when you drop subframe to change the captive nuts brake the welds in the subframe which is a pain on the near side as you have to open the chassis then weld back up/ early ones suffered with rear subframe bushes but most were sorted from factory/rear washer jet always pops its joint on inside of car in quarter panel/rear tyres always wear out of shape if you run budget tyres!!/high mileage wheels always seem to corrode and leak from around the bead/apart from that with reg services and especially fuel filter changes they are pretty bullet proof!!! Like any car mate if your buying one get the best you can for your budget and if been looked after most issues would of been done by previous owners. Hope I haven't put you off too much lol!!!