PACCAR PX-9 CM2350 (2013-17) Fault Code:1668-3 PID:203C SPN:1761 FMI:4 Aftertreatment 1 Diesel Exhaust Fluid Tank Level Sensor Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
Aftertreatment Diesel Exhaust Fluid Tank Level Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the aftertreatment diesel exhaust fluid tank level sensor circuit.

Effect:
Possible reduced engine performance

Circuit Description:
The aftertreatment diesel exhaust fluid quality sensor is a smart device that communicates to the ECM via the J1939 datalink. The aftertreatment diesel exhaust fluid quality sensor performs its own internal diagnostics and reports malfunctions back to the primary engine contol module via the J1939 datalink. The aftertreatment diesel exhaust fluid quality sensor is used to measure the concentration of the aftertreatment diesel exhaust fluid in the tank.

Component Location:
The aftertreatment diesel exhaust fluid tank level sensor is located in the aftertreatment diesel exhaust fluid tank. Location of the tank and level sensor is OEM dependent. Refer to the OEM service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid tank level sensor signal voltage was out of range low.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
2) 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 amber CHECK 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:
The type of diesel exhaust fluid tank temperature and level sensor used can vary depending on the vehicle OEM. As a result, the physical and/or electrical sensor configuration may vary slightly from what is shown in the troubleshooting and wiring diagram information.

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) Signal circuit open or shorted to ground in the engine harness or sensor
2) Supply line open or shorted to ground