Circuit DescriptionThe aftertreatment diesel exhaust fluid temperature sensor is used by the diesel exhaust fluid controller to monitor the temperature of the aftertreatment diesel exhaust fluid inside the diesel exhaust fluid tank. The diesel exhaust fluid controller monitors the voltage on the SIGNAL pin, converts this to a temperature value, and communicates that value to the ECM via the engine data link.

Component LocationThe aftertreatment diesel exhaust fluid temperature sensor is located in the diesel exhaust fluid tank. The location of the tank, line heaters, and temperature sensor is OEM dependent. Refer to the OEM service manual.

Conditions for Running the DiagnosticsThis diagnostic runs when the diesel exhaust fluid tank temperature is being maintained by using the diesel exhaust fluid tank heater or when line heating is being requested.

Conditions for Setting the Fault CodesThis fault code is set when the diesel exhaust fluid tank temperature has been at normal operating levels, but is no longer able to maintain the proper temperature, and is in danger of freezing.

This fault code can also set when heating of the diesel exhaust fluid lines, tank, or dosing unit, can not be achieved.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.The diesel exhaust fluid dosing unit will purge itself, and diesel exhaust fluid injection into the aftertreatment system is disabled.Conditions for Clearing the Fault CodeTurn the keyswitch to the OFF position for 2 minutes to allow the system to completely powerdown. Turn the keyswitch to the ON position.The fault code status in INSITE? electronic service tool will change to INACTIVE immediately after the system is able to adequately heat and the diagnostic runs and passes. If heating can not be completed, use the “Diesel Exhaust Fluid Doser System Heater Test” found under “ECM Diagnostic Test” in INSITE? electronic service tool to command heating to the tank heater and all line heaters.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where 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 TalkThis fault code can also set if heating of the aftertreatment DEF lines can not be achieved. Troubleshoot all line heater fault codes prior to Fault Code 3651.

Possible causes of this fault code include:

Blocked or restricted coolant flow to the diesel exhaust fluid tank heaterDisconnected or broken tank heater coolant supply hoseMalfunctioning or stuck closed diesel exhaust fluid tank heater control valveMalfunctioning or stuck aftertreatment diesel exhaust fluid tank temperature sensorOperation in extremely cold ambient conditions.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 Cause:1) DEF fluid tank temperature sensor failure2) DEF fluid tank heater control valve failure3) ECM calibration