Circuit DescriptionThe crankcase pressure sensor is used to monitor the pressure inside the crankcase. The 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 in the crankcase filter assembly.

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 operating.

Conditions for Setting the Fault CodesThe ECM detects that the crankcase pressure sensor is reading an erratic value at key ON or the crankcase pressure reading is 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) immediately when the diagnostic runs and 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 driving and steady state highway 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 Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostic (OBD) engines, the ECM will turn off the 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 hose instulation2) Crankcase breather element instulation3) Crankcase breather filter failure4) ECM failure