the faults havent been cleared, the record of what the various sensors give when something amiss called fault codes which are stored so can be read to help diagnose a problem have been cleared ,and will need to be read again ,for instance if a code that was to do with the amount of air going into engine you would look at relavent sensors and also things like turbo wastegate seizing thus allowing over boost or blocked air filter ,poor pipe etc,i woulkd recommend anyone to buy their own hawkeye or similar so that you can read codes ,even if you dont understand someone here will cheaper in long run,i would look up seized wastegate on here and try that first ,then get codes read and come back with them ,you may have a good man helping you or he could just change everything till he gets it and you a large bill