Circuit DescriptionThe crankcase pressure sensor is used to monitor the pressure inside the crankcase. The engine control module (ECM) supplies the crankcase pressure sensor a 5 volt reference voltage. When the crankcase pressure is low, the sensor signal voltage is low. When the crankcase pressure is high, the sensor signal voltage is near the 5 volt reference voltage. The ECM monitors the crankcase pressure signal circuit voltage to calculate the pressure of the air within the crankcase.

Component LocationThe crankcase pressure sensor is located near the crankcase ventilation filter.

Conditions for Running the DiagnosticsThis diagnostic consists of two parts. The first part of this diagnostic runs at initial key ON and the second part runs when the engine is running.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected the crankcase pressure sensor was reading an erratic value at key ON or the crankcase pressure reading was not changing with engine operating conditions.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkThis fault code can be caused by a crankcase breather hose disconnected between the engine outlet and crankcase filter assembly on engines with an externally mounted crankcase filter option.

Possible causes of this fault code include:

Resistance in the wiring harnessA malfunctioning in-range pressure sensorCrankcase pressure sensor is not installed correctly in the housing.

Possible Cause:1) Crankcase breather hose2) Oil Fill cap3) Crankcase breather filter failure4) ECM failure