Scania fault code 4521

Code 4521 is used by 2 different Scania systems. Choose the control unit shown in your diagnostic tool:

EMS Engine Management System Relay to injectors R651 The engine control unit indicates a short circuit to voltage supply. Read explanation → ZF ZF gearbox Proportional valve, retarder (Y1) Incorrect signal from the retarder proportional valve. Read explanation →