Cummins ISX CM870 (2003-06) Fault Code: 2373 PID: P95 SPN: 1209 FMI: 3/3 Exhaust Gas Pressure Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the exhaust gas pressure circuit.

The exhaust gas pressure sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active.
Possible causes:

1)An open return circuit in the engine harness, connectors, or sensor.
2)A signal wire shorted to sensor supply or battery voltage.

Possible repairs:

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