Cummins ISX12 CM2250 (2010-12) Fault Code: 125 PID: 102 SPN: 102 FMI: 18 Intake Manifold 1 Pressure- Data Valid But Below Normal Operating Range- Moderately Severe Level

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.

If the ECM detects that the necessary charge flow into the engine is below the minimum limit for a period of time, this fault code is logged.

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

Conditions for Running the Diagnostics
This diagnostic only runs when the engine is operating.

Conditions for Setting the Fault Codes
The ECM detects that the intake manifold pressure signal reading is below the expected level for the present engine operating conditions.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE after the engine is able to achieve the desired oxygen level necessary for complete combustion and the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
For on-board diagnostics (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 engines.

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 variable geometry turbocharger and exhaust gas recirculation 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 of this fault are:

Leaks in the air intake system between the turbocharger and intake manifold
A damaged intake manifold pressure sensor
A damaged barometric pressure sensor
Restriction in the charge-air cooler
Leaks or restrictions in the exhaust gas recirculation system plumbing
Fuel inlet restriction too high (normally caused by a restricted fuel filter)
Restriction in the air filter
Restriction in the exhaust system.

Possible Cause:
1) Charge-air cooler failure
2) Intake Manifold temperature/Pressure sensor failure
3) ECM calibration