PACCAR PX-8 CM2150 (2007-09) Fault Code: 123 PID: 102 SPN: 102 FMI: 4 Intake Manifold 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage or open circuit detected at the intake manifold 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 intake manifold 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 Fault Code 123, check for multiple faults.

Possible causes :

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

Possible repairs:

1)Replace the intake manifold pressure sensor.
2)The removal and installation of the connector may correct the problem.
3)Replace the ECM.
4)Repair or replace the engine harness.