Not really common faults as such mate. Just what you should expect from a 15 year old turbo car. Check underneath the car for rust, inside the engine bay and boot. Check the engine for oil leaks or a creamy mayo like stuff on the dipstick and the oil cap. Check the coolant is relatively decent. Check all the electrics which to be fair are normally bullet proof. Make sure the engine is cold start it and check for blue or black smoke at the tailpipe with an oily smell. Steam is ok when the cars cold in this cold weather. Take it a run and dont be scared to get the foot down it should pull well and give you 3 green lights when you get past 3.5k if its standard. Check for smoke on top end of rev range. Feel like im stating the obvious but its easy to forget when buying a car a lot of people see it and the blinkers are on.