P051D OBD II Trouble Code Crankcase Pressure Sensor Circuit High

How to quickly diagnose, repair, and causes of a P051D trouble code which indicates a detected high voltage condition within the crankcase pressure sensor circuit.

Symptoms of P051D OBD II Trouble Code

  • Reduced fuel economy
  • Leaking gaskets
  • Fuel smells
  • CEL (Check Engine Light) illuminated
  • Engine performing abnormally
  • Sludge in oil
  • Engine smoking black soot
  • High/Low internal crankcase pressures

Common Causes of P051D OBD II Trouble Code

  • Crankcase pressure sensor defective
  • Internal electrical issue within the sensor
  • ECM issue
  • PCV (Positive Crankcase Ventilation) valve defective
  • PCV issue (broken runners/tubes, disconnected, chafed lines, etc.)
  • Clogged PCV system
  • Sludgy oil (moisture present)
  • Water intrusion
  • Engine over-filled with oil

Severity of P051D OBD II Trouble Code

I would say, in the grand scheme of things, this fault would be considered moderate-low. Basically, if it fails, you don't run the risk of immediate drastic further damage. I say this to stress the point that, it needs to be addressed sooner rather than later. Earlier, I mentioned some of the possible issues if left neglected so keep these in mind.