P20BE

P20BE-(DIESEL EXHAUST FLUID) REDUCTANT PRESSURE LINE HEATER CONTROL CIRCUIT PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation

The Diesel Exhaust Fluid (DEF) Tank has an internal heating coil to help eliminate freezing of Diesel Exhaust Fluid. The DEF Dosing Control Unit monitors the temperature of the Diesel Exhaust Fluid inside the tank. When it is determined that the Diesel Exhaust Fluid needs to be heated, the DEF Dosing Control Unit opens the DEF Engine Coolant Valve which is located nest to the DEF Tank, and allows warm engine coolant to circulate through the heating coil inside the tank to warm the Diesel Exhaust Fluid in the tank. The DEF Dosing Control Unit will stop dosing fluid into the after treatment system and the purge the system. The DEF Dosing Control Unit will illuminate the MIL lamp via the PCM immediately after this diagnostic runs and fails. The DEF Dosing Control Unit will turn off the MIL lamp via the PCM immediately after the diagnostic runs and passes for three consecutive key cycles.

- When Monitored:
This monitor runs when the DEF Tank temperature is being maintained by using the DEF Tank Heater.

- Set Condition:
There are two conditions that will set this DTC. The first is if the DEF Dosing Control Unit detects that the DEF Tank temperature drops from above defrosted temperature, 41°F (5°C) to below frozen temperature, 0°F. The second is if there are any line heater continuity faults present for any of the heater circuits in the system.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

NOTE: The DEF Line Heater monitor runs only when the DEF Line Heater Relay is commanded on. If the ambient temperature is too warm for the DEF Line Heaters to be turned on, the DTC will remain active and will not be able to be erased after repair is completed. Using the scan tool, navigate to Actuator Tests and actuate the Line Heater Relay test for the appropriate Line Heater to run the diagnostic and determine if the repair has been completed. If the repair is complete, the fault will move to stored and be able to be cleared with the scan tool.

1. CHECK THE ENGINE COOLANT LEVEL

NOTE: If there are DTCs present for the DEF Line Heaters or DEF Supply Pump Assembly Heater, perform those diagnostic procedures before continuing with this test procedure.

1. Turn the ignition off.
2. Verify the engine coolant level.

Is the engine coolant level above the minimum?

Yes

- Go To 2

No

- Fill the engine coolant to the proper level.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

2. CHECK FOR RESTRICTED OR LEAKING ENGINE COOLANT LINES/HOSES
1. Visually inspect the engine coolant supply and return lines for signs of a restriction or leaks.

Were any restrictions or leaks found?

Yes

- Repair or replace the engine coolant lines.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. CHECK FOR RESTRICTED DIESEL EXHAUST FLUID TANK HEATER
1. Remove the coolant lines at the DEF Tank Heater Coil.
2. Blow regulated low pressure shop air through the DEF Tank Heater Coil.

Were any restrictions found?

Yes

- Replace the DEF Tank Heater Coil. Diesel Exhaust Fluid Level/Temperature Sensor - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the DEF Engine Coolant Control Valve. Diesel Exhaust Fluid Engine Coolant Control Valve - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.