Cummins ISX12 CM2250 (2010-12) Fault Code: 295 (BCL) PID: 108 SPN: 108 FMI: 2 Barometric Pressure- Data Erratic, Intermittent, or Incorrect

Circuit Description
The combination turbocharger compressor intake pressure/temperature sensor is used to measure ambient air pressure. The pressure measuring portion of the sensor responds to pressure changes in the atmospheric pressure, which occur based on elevation at which the engine is presently operating. The turbocharger compressor intake pressure sensor has a 5 volt supply circuit, a pressure sensor signal voltage, and a return circuit. The electronic control module (ECM) will detect a low signal voltage when the vehicle is operating at high altitudes. The ECM will detect a high signal voltage when the vehicle is operating at sea level altitudes.

Component Location
The combination turbocharger compressor intake pressure/temperature sensor is located in the original equipment manufacturer (OEM) intake air plumbing.

Conditions for Running the Diagnostics
This diagnostic consists of two parts.

One part runs immediately after the keyswitch is turned OFF, and the engine coolant temperature is above 70?C or 158?F.

The other part runs continuously when the engine is operating.

Conditions for Setting the Fault Codes
The ECM detects that the compressor intake pressure reading is higher or lower than the other absolute pressure sensors on the engine, or an in-range malfunction of the sensor has been detected.

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.
A default value of the compressor intake pressure reading is used.
Diesel exhaust fluid injection into the aftertreatment system is disabled.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The exhaust gas recirculation (EGR) valve will be closed.
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
To validate the repair, first make sure the engine coolant temperature is above 70?C or 158?F. Operate the engine if necessary
Cycle the keyswitch to the ON position for 3o seconds, then cycle the keyswitch to the OFF position for 30 seconds. Start the engine and let it idle for 1 minute.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
For On-Board Diagnostic (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
After key OFF, when the engine is warm, the sensor readings for various engine pressure sensors on the engine are compared with the compressor intake pressure. This fault code occurs if the compressor intake pressure sensor reading is different from the other sensor readings. This fault can also be set if a compressor intake pressure reading higher or lower than what is possible is detected.

Possible causes of this fault code include:

Malfunctioning compressor intake pressure sensor
High resistance in the compressor intake pressure sensor signal or return lines
Plugged or highly restricted air filter can also possibly cause this fault to become active, especially at higher altitudes.

Possible Cause:
1) ECM failure