DTC P0551: Power Steering Pressure Sensor Circuit Range/Performance

CIRCUIT OPERATION
• A battery positive voltage is applied to the power steering pressure switch output terminal (terminal 1) from the PCM (terminal 52) via the resistor in the PCM.
TECHNICAL DESCRIPTION
• The power steering pressure switch converts the existence of a power steering load into a high/low voltage, and inputs it into the PCM.
• When the steering wheel is turned, hydraulic pressure rises. The power steering pressure switch closes, and the applied battery positive voltage will be grounded. With this, the power steering pressure switch output voltage will fluctuate between 12 volts and 0 volt.
• While driving with the steering wheel held straight, the power steering pressure switch turns "OFF".
• The PCM checks whether the power steering pressure switch turns "OFF" or "ON" during driving.
DESCRIPTIONS OF MONITOR METHODS
Power steering pressure switch stays on during specified go/stop operations.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
• Not applicable

Sensor (The sensor below is determined to be normal)
• Engine coolant temperature sensor
DTC SET CONDITIONS Logic Flow Chart


Check Conditions
Engine coolant temperature is higher than 30°C (86°F).
Repeat 10 or more time: drive*1, stop*2
Drive*1: Vehicle speed is 50 km/h (31 mph) or more for 4 seconds.
Stop*2: Vehicle speed is 1.5 km/h (0.9 mph) or lower.

Judgment Criteria
• Power steering pressure switch continues to be "ON".
OBD-II DRIVE CYCLE PATTERN
None.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:
• Power steering pressure switch failed.
• Open or shorted power steering pressure switch circuit, harness damage or connector damage.
• PCM failed.