Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P0554 Power Steering Pressure Sensor/Switch Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Hydraulic power steering has a pressure switch or sensor on the high-pressure line; when the wheel is turned at standstill, pump pressure and engine load rise sharply, so the engine module raises idle air in advance to stop the engine stalling. That makes it an input to idle control under CARB. Switches (Saab, Mitsubishi) ground a pull-up; analogue 5 V sensors (Toyota) give about 0.45 V at zero pressure. GM's and Ford's tables do not use P0550–P0554. P0554 means the signal flutters. Mitsubishi sets it when the switch changes state at 10 Hz or more for 20 s above 50 km/h – no sound switch switches that fast. Causes are electrical (loose contact) as well as hydraulic: pressure pulsation from air or low fluid, or an unsteady pump.

Likely causes

Loose contact or corrosion at connector or wire
Low fluid or air in the system (pressure pulsation)
Pressure switch worn (contact bounce)
Steering pump delivering unsteady pressure

Symptoms

  • Idle speed jumping or fluctuating
  • Check engine light depending on the maker
  • Steering pump noise (air, low fluid)

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–250
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

power steering pressure switchsensor wiringengine control module

Related codes

P0550P0551P0552P0553P0506

References: mitsubishitechinfo.com, law.cornell.edu.