PACCAR PX-6 CM2150 (2007-09) Fault Code: 1663 PID: SPN: 3241 FMI: 11 Catalyst Inlet Temperature Sensor Swapped with Outlet – Condition Exists. The inlet and outlet catalyst temperature sensor connections are swapped.

Verify the 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, calibrate the ECM.

This fault code is activated when the ECM determines that the temperature reading from the aftertreatment diesel oxidation catalyst inlet temperature sensor and the aftertreatment diesel particulate filter inlet temperature sensor are reading backwards. The most likely cause of this fault code is that the aftertreatment diesel oxidation catalyst inlet temperature sensor and the aftertreatment diesel particulate filter inlet temperature sensor connectors are swapped at the OEM harness.

The diesel oxidation catalyst inlet temperature sensor and the diesel particulate filter outlet temperature sensor are the same part number and have the same electrical connections. The diesel particulate filter inlet temperature sensor has a different connector key to prevent it from being swapped with the other temperature sensors. Verify that the aftertreatment temperature sensors are correctly installed.

An in-range failure of the aftertreatment diesel oxidation catalyst or the aftertreatment diesel particulate filter inlet temperature can cause this fault code. Make sure there are not any fault codes related to the aftertreatment temperature sensors before following this troubleshooting tree.

Possible repairs:

1)If no short is found, replace the temperature sensor that is reading higher or lower than the other sensors.