I have just purchased a 2005 C230 Kompressor with a code P0128. What could my problem be. I have read that alot of people say a simple thermostat swap will cure the problem but I have read where alot of people say that it isn't a thermostat issue. Just wanting to see if I could get a definite answer on what this particular code means and what part is faulty. I have tried resetting it time and time again but it just comes back after about 15 minutes of driving. All help is appreciated.