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

P051D Crankcase Pressure Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The crankcase pressure sensor measures pressure in the crankcase ventilation (PCV) against atmosphere; Ford's EcoBoost engines use it for the disconnection check P04DB, which needs a sound sensor. P051D means the signal is too high – Ford sets it above 4.56 V for 5 s. Typical is a signal shorted to 5 V or battery voltage, an open sensor ground, or an open signal pulled up. A real excess pressure in the crankcase does not set P051D.

Likely causes

Sensor ground open
Signal line shorted to positive
Sensor faulty
Engine module

Symptoms

  • Check engine light on
  • Usually no change in driving
  • Disconnection check P04DB suspended

Repair estimate

DifficultyEasyDIY possible
Parts and labour€40–200
Time0.3–1.5 h

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

Parts involved

crankcase pressure sensorsensor wiringengine control module

Related codes

P051AP051BP051CP051EP053E

References: fordservicecontent.com, static.nhtsa.gov.