Could be a bad wheel bearing, or the EBCM. Clean/check all the connectors at the hubs, clear the codes and see if it comes back. If it does then you need to have the EBCM rebuilt (the ABS control module).

C0550 is an internal malfunction in the ABS/traction control module

C0450 Steering Assist Control Solenoid/Motor/Actuator Circuit = EBCM