PACCAR PX-9 CM2350 (2013-17) Fault Code:125 PID:102 SPN:102 FMI:18 Intake Manifold 1 Pressure – Data Valid But Below Normal Operating Range – Moderately Severe Level

Reason:
Intake Manifold 1 Pressure – Data Valid But Below Normal Operating Range – Moderately Severe Level. Intake manifold pressure is below the minimum operating limit.

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 engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the intake manifold pressure reading was below the expected level for the engine operating conditions.

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) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
3) 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, it may be necessary to operate the vehicle on a chassis dynamometer or to drive the vehicle in order to get the engine load high enough for the diagnostic to run.
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) 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 1 pressure sensor monitors pressure in the intake manifold. This fault is set active when the intake manifold pressure is too low for the present engine operating conditions. The ECM commands a charge flow command and the VGT and EGR valve move to meet this command. If the engine is unable to achieve the desired oxygen level necessary for complete combustion, this fault code is logged.

Possible Causes:
1) Leaks in the air intake system between the turbocharger and intake manifold
2) A damaged intake manifold pressure sensor
3) A damaged barometric pressure sensor
4) Restriction in the charge-air cooler
5) Leaks or restrictions in the EGR system plumbing
6) Fuel inlet restriction too high (normally caused by a restricted fuel filter).