Overview
Code
Fault Code: 1668 (3-Wire Sensor)
PID: P203C
SPN: 1761
FMI: 4
LAMP: Amber
SRT:
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 tank level sensor is used to monitor the aftertreatment diesel exhaust fluid level inside the aftertreatment diesel exhaust fluid 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
- The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
- 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
- To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
- The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
- The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
- 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
Possible causes of this fault code include:
- Signal circuit open or shorted to ground in the engine harness or sensor
- Supply line open or shorted to ground.
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.
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