Cummins ISB6.7 CM2150 (2007-09) Fault Code: 1674 PID: SPN: 3249 FMI: 4 Aftertreatment Exhaust Gas Temperature 2 Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the aftertreatment diesel particulate filter inlet temperature sensor circuit.

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.

The aftertreatment diesel particulate filter inlet temperature sensor shares return wires in the OEM harness with other sensors. A shorted return can cause multiple fault codes to be active.

Possible causes:

1)Signal shorted to ground in the harness
2)Signal shorted to return or ground in the sensor.

Possible repairs:

1)Replace the aftertreatment diesel particulate filter inlet temperature sensor.
2)The removal and installation of the connector may correct the fault.
3)Replace the ECM.
4)Repair or replace the OEM harness and/or the aftertreatment harness.