Cummins ISB6.7 CM2150 (2007-09) Fault Code: 1844 PID: 101 SPN: 101 FMI: 4 Crankcase Pressure Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the crankcase pressure circuit.

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM.

The crankcase pressure sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting, check for multiple fault codes.

Possible causes:

1)Signal circuit open or shorted to ground in the engine harness or sensor
2)Supply wire open or shorted to ground.

Possible repairs:

1)Replace the crankcase pressure sensor.
2)Repair or replace the engine harness.
3)Replace the ECM.