x_dubway Posted January 6, 2019 Report Share Posted January 6, 2019 Just recently had my car mapped. Its a 2005 320cd. Anybody know what could be causing the error code 4521. The car gets thrown into limp mode when high boost is held for a while i.e motorway. The code reads 4521 : Charge pressure control small turbo control deviation TIA Link to comment Share on other sites More sharing options...
