PACCAR PX-9 CM2350 (2013-17) Fault Code:1621 PID:137 SPN:1387 FMI:4 Auxiliary Pressure Sensor Input 1 Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
Auxiliary Pressure Sensor Input 1 Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected on the original equipment manufacturer (OEM) pressure sensor circuit.

Effect:
None on performance

Circuit Description:
The original equipment manufacturer (OEM) has the option of wiring a pressure or temperature sensor input to the Cummins® engine control module (ECM). A specific calibration is then created to recognize this pressure or temperature sensor input. This fault code is activated when the pressure or temperature input from the OEM sensor exceeds the engine protection limit defined by the OEM. Depending on OEM requirements, an Engine Protection derate can be associated with this fault code.

Component Location:
The OEM pressure sensor input and location will vary. Refer to the OEM service manual for sensor location.

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 low voltage on the control signal circuit

Action Taken When the Fault Code is Active:
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code:
1) To validate the repair, 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) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE 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.

Shop Talk:
N/A

Possible Causes:
1) Signal circuit open or shorted to ground in the engine harness or sensor
2) Supply line open or shorted to ground