PACCAR PX-6 CM2150 (2007-09) Fault Code: 1691 PID: SPN: 3250 FMI: 13 Catalyst Efficiency – Out of Calibration. The temperature increase across the aftertreatment diesel oxidation catalyst is lower than expected.

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, calibrate the ECM.

This fault code is logged when the conversion efficiency of the DOC is calculated to be less than that required to perform an effective regeneration.

Possible causes:

1)Soot plugging the front face of the aftertreatment diesel oxidation catalyst
2)Engine oil or fuel contamination of the aftertreatment diesel oxidation catalyst
3)A cracked or contaminated aftertreatment diesel oxidation catalyst
4)A leaking exhaust system between the turbocharger and the diesel oxidation catalyst.
5)Excessive automatic/stationary regenerations causing soot plugging on the front face of the aftertreatment diesel oxidation catalyst.

An in-range malfunction of the aftertreatment diesel oxidation catalyst temperature sensor or the aftertreatment diesel particulate filter inlet temperature sensor 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 necessary, calibrate the ECM.
2)Repair or replace the damaged or leaking exhaust system components.
3)Replace the aftertreatment DOC.