My wife has a 2002 XC70 with 64K miles. Vehicle has been throwing P0236 & P0237 codes which have to do with the turbo boost sensor. I have already checked hoses and wiring. Everything appears to be OK. Freeze frame show the codes always set before the engine is up to operating temperature. I cleared the codes yersterday and as soon as the car was started today the codes were back. I drove the car and noticed, especially when the engine is cold, a hesitation when initially pressing the accelerator. It will sometimes hesitate when the engine is warm but it is much less noticable. The hesitation is like a carburated vehicle with a bad accelerator pump. Full throttle it runs great. Turbo kicks in and will run up to 6K with no problem. Any suggestions? She only uses premium fuel and the oil is changed ever 5-6K miles with Mobil 1. I'm thinking of taking it to the dealer but if it is something simple would rather fix it myself.