Cummins ISB4.5 CM2150 Fault Code: 1942 PID: 101 SPN: 101 FMI: 2 Crankcase Pressure – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The 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 Location
The crankcase pressure sensor is located in the crankcase filter assembly.

Conditions for Running the Diagnostics
This 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 Codes
The 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 Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails

Conditions for Clearing the Fault Code
-To validate the repair, perform a key cycle and leave the key in the ON position for 1 minute. Then start the engine and let it idle for 2 minutes.
-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 Talk
This 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
-Resistance in the wiring harness
-A malfunctioning in-range pressure sensor
-Crankcase pressure sensor is not installed correctly in the housing.