We have this machine at work It is a good cleaner and does remove carbon deposits if used as a preventive maintenance tool on servicing. but if you have a vehicle with a heavy deposit of carbon in the intake system then its not very efficient and will cause issues as carbon deposits travel down into the combustion chamber and then into exhaust system, it will clean the system but you have to keep pumping more and more chemical cleaner into it and we have found to use approx. 6 ltr of cleaner and 1ltr of rinse agent to get a vehicle clean with a material cost of just over £100 and then you have a additional cost of the fuel injector cleaner, also I used this on my brothers high mileage bmw530d which caused the throttle body to fail as the chemical manage to pass the seal into the printed circuit board.