PACCAR PX-6 CM2150 (2007-09) Fault Code: 1666 PID: SPN: 3241 FMI: 3 Aftertreatment Exhaust Gas Temperature 1 Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the catalyst 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 oxidation catalyst inlet temperature sensor shares return wires in the OEM harness with other sensors. A shorted return wire can cause multiple fault codes to be active.

Possible causes:

1)Open return circuit in the harness, connectors, or sensor
2)Open signal circuit or shorted to a voltage source.

Possible repairs:

1)Replace the aftertreatment diesel oxidation catalyst inlet temperature sensor.
2)The removal and installation of the connector may correct the fault.
3)Replace the ECM.
4)Replace the OEM harness.
5)Replace the aftertreatment harness.
6)Replace all interconnects.