The hydraulically assisted system consists of a steering pump that is driven by a belt, plus a steering box, hoses or lines, and some sensors. The ECM (Engine Control Module) works in conjunction with the Power Steering Pressure Sensor (PSP) to control the pressure within the system. Besides, adjustments are made if necessary.
The Check Engine light is lit next to the DTC code setting P0550 OBDII when one or more conditions are identified which are outside the specified range for the PSP Sensor circuit. Usually, this code is due to electrical problems, but mechanical failures are not ruled out.