PACCAR PX-8 CM2150 (2007-09) Fault Code: 295 PID: 108 SPN: 108 FMI: 2 Barometric Pressure – Data Erratic, Intermittent, or Incorrect. The ambient air pressure sensor is reading an erratic value at initial key-on.

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.

At key-on, before the engine starts, the sensor readings for intake manifold pressure, exhaust gas pressure (if equipped), and engine oil pressure (if equipped) are compared with the barometric pressure. This fault code occurs if the barometric pressure sensor reading is different from the other three. This check is only done once after the keyswitch is turned on.

Possible causes:

1)Stuck in-range barometric pressure sensor reading.
2)High resistance in the barometric pressure sensor signal or return lines.

On ISB applications, this fault code will go active if the intake manifold pressure/temperature sensor is accidentally installed in the ambient air temperature/pressure sensor location. These sensor appear the same on the outside and can be accidentally interchanged.

Possible repairs:

1)Replace the barometric pressure sensor.
2)Replace the ECM.
3)Repair or replace the engine harness.