PACCAR PX-9 CM2350 (2013-17) Fault Code:222 PID:108 SPN:108 FMI:4 Barometric Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
Barometric Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at barometric pressure circuit.

Effect:
Possible reduced engine performance.

Circuit Description:
The barometric pressure sensor responds to pressure changes in the atmospheric pressure. The pressure changes occur based on the elevation where the engine is presently operating. The barometric pressure sensor has a 5 volt supply circuit, a sensor signal voltage, and a return circuit.

Component Location:
The barometric pressure sensor is mounted on the main branch of the engine harness near the ECM.

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 barometric air 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 for the barometric pressure reading is used.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) Diesel exhaust fluid injection into the aftertreatment system is disabled.
5) 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 ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
3) 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.
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:
N/A

Possible Causes:
1) A short circuit to ground in the engine harness
2) An open circuit in the engine harness
3) A malfunctioning barometric air pressure sensor
4) A malfunctioning engine control module (ECM)