PACCAR PX-9 CM2350 (2013-17) Fault Code:3235 PID: SPN:4363 FMI:16 Aftertreatment SCR Outlet Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level

Reason:
Aftertreatment SCR Outlet Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level. The SCR outlet temperature sensor reading has exceeded the maximum temperature limit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment SCR (selective catalytic reduction) temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment SCR temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment SCR temperature sensor module is used to measure the aftertreatment SCR intermediate temperature and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment SCR temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment SCR temperature sensor module is mounted on the aftertreatment SCR catalyst.

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 Engine Control Module (ECM) detected the temperature at the SCR catalyst outlet temperature sensor was greater than 650°C [1202°F] for more than 60 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) Diesel exhaust fluid injection into the aftertreatment system is disabled.
3) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

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 SCR outlet temperature drops 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.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Causes:
1) Malfunctioning SCR catalyst
2) Degraded, diluted, or incorrect diesel exhaust fluid
3) Malfunctioning in-range SCR outlet temperature sensor