PACCAR PX-9 CM2350 (2013-17) Fault Code:123 PID:102 SPN:102 FMI:4 Intake Manifold 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
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.

Effect:
Possible reduced engine performance.

Circuit Description:
The engine control module (ECM) provides a 5 volt supply to the intake manifold pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The intake manifold pressure sensor provides a signal to the ECM on the intake manifold pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the intake manifold.

Component Location:
The intake manifold 1 pressure/temperature sensor is located in the air intake horn.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the intake manifold pressure signal voltage was out of range low.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) A default value of the intake manifold pressure reading is used.
3) Diesel exhaust fluid injection into the aftertreatment system is disabled.
4) Active and stationary regeneration of the diesel particulate filter will be disabled.
5) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
6) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) 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.
5) 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:
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.
3) Malfunctioning intake manifold pressure/temperature sensor