New Holland DCU 19109 – DCU: Short circuit high in UREA (DEF/Reagent) tank temperature sensor

The system is detecting an electrical signal from the sensor that is higher than the expected range, meaning the sensor or its circuit is shorted to a high voltage source.

• New Holland T7
• New Holland T8
• New Holland T9

1. 1

   Turn off the ignition and allow the engine to cool.

2. 2

   Locate the DEF tank header unit, which houses the integrated temperature, level, and quality sensors.

3. 3

   Disconnect the electrical connector at the DEF tank sensor and inspect the harness and pins for damage, corrosion, or pushed-out pins.

4. 4

   Use a multi-meter to check the wiring harness between the sensor and the DCU for a short circuit to voltage. Test the sensor pins against the chassis ground to see if unwanted voltage is present.

5. 5

   If voltage is present on the ground or signal return lines, repair the wiring harness. If the harness tests good, the internal temperature sensor within the DEF header unit has failed.

1. 1

   Depressurize system

   Ensure the machine is turned off and the DEF system is depressurized and cooled down.

2. 2

   Clean tank area

   Clean the area around the top of the DEF tank to prevent dirt or debris from falling into the tank.

3. 3

   Disconnect electrical connector

   Disconnect the main electrical connector from the DEF tank header unit.

4. 4

   Disconnect fluid lines

   Disconnect the DEF fluid lines attached to the header unit (be prepared to catch any spilled DEF fluid).

5. 5

   Unbolt mounting flange

   Unbolt or unthread the mounting flange/seal that secures the DEF head unit to the tank.

6. 6

   Remove old header unit

   Carefully pull the old DEF header assembly out of the tank.

7. 7

   Install new header unit

   Install the new DEF header unit with a new mounting seal to prevent leaks.

8. 8

   Reconnect lines and connector

   Reconnect the DEF fluid lines and the electrical connector.

9. 9

   Clear fault codes

   Turn on the ignition and use a diagnostic scan tool to clear the DCU 19109 / P205D fault code from the Dosing Control Unit.