PACCAR PX-6 CM2150 (2007-09) Fault Code: 1966 PID: 326 SPN: 3241 FMI: 0 Aftertreatment Exhaust Gas Temperature 1 – Data Valid But Above Normal Operating Range – Most Severe Level. Engine exhaust gas temperatures entering the aftertreatment system are above the engine protection limits.

This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel oxidation catalyst and/or aftertreatment diesel particulate filter.

Possible causes:

1)Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2)A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system
3)The aftertreatment diesel oxidation catalyst inlet temperature sensor failed in-range
4)The aftertreatment diesel particulate filter inlet temperature sensor failed in-range
5)The aftertreatment diesel particulate filter outlet temperature sensor failed in-range
6)An in-range engine sensor malfunction has occurred, causing excessive fuel to enter the exhaust system.

The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damage and reuse. For ISB CM2150 engines, use the following procedure in the ISB CM2150 Service Manual, Bulletin 4021578. Refer to Procedure 014-013 in Section 14. For ISC and ISL CM2150 engines, use the following procedure in the ISC and ISL CM2150 Service Manual, Bulletin 4021569.

Possible repairs:

1)Repair or replace any damaged components.
2)Replace the injector.
3)Repair or replace any components that caused the engine oil or diesel fuel contamination.