PACCAR PX-9 CM2350 (2013-17) Fault Code:3255 PID: SPN:3246 FMI:16 Aftertreatment Diesel Particulate Filter Outlet Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level

Reason:
Aftertreatment Diesel Particulate Filter Outlet Temperature – Data Valid But Above Normal Operating Range -Moderately Severe Level. The aftertreatment diesel particulate filter outlet temperature sensor reading has exceeded the maximum engine protection temperature limit.

Effect:
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamps starts flashing.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter outlet temperature sensor is located in the aftertreatment system. It is located at the outlet of the aftertreatment diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault Codes:
The aftertreatment diesel particulate filter intake temperature sensor reading was greater than 687°C [1269°F] for 90 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) Active and stationary regeneration of the diesel particulate filter will be disabled.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
5) The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault will go inactive immediately after the aftertreatment temperatures drop below the warning limit, and will likely be inactive when the vehicle is in the shop. For these reasons, this troubleshooting tree must be used for both active and inactive fault codes.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

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) A face plugged aftertreatment diesel oxidation catalyst