The power steering system increases steering performance and improves steering feel and power-saving effectiveness. The power steering pressure switch senses the power steering load and converts it into a voltage (high/low) signal to the PCM. The PCM then controls the idle speed control motor by using the voltage signal from the power steering pressure switch.
The PCM monitors the power steering switch and can determine when the signal is outside of the possible range of the switch. When the signal is out of range for a prolonged period of time, the PCM will set DTC P0551.
Item
Detecting Condition
Possible Cause
DTC Strategy
Plausibility check
Poor connection or damaged harness
Faulty power steering pressure sensor
Enable Conditions
Vehicle speed >37mph
Coolant temp. >60?(140?)
No relevant failure
Threshold Value
Signal stuck
Diagnostic Time
200 sec.
MIL On Condition
-