New Holland DCU 19649 – DCU: UREA Tank level error

The system has lost communication with the Diesel Exhaust Fluid (DEF / AdBlue) tank level sensor. The controller is either detecting an open electrical circuit on the sensor's supply line or is failing to receive the expected SAE J1939 CAN-BUS signal regarding the fluid level.

• T5
• T6
• T7
• T8
• T9
• T5.110
• T7.315
• T8.390
• T9.700
• CR
• CX
• CR8.90
• CX8.80
• FR
• FR500
• FR900
• B95C Backhoe Loaders
• L220 Skid Steers

1. 1

   Visually inspect the wiring harness connecting the DEF tank level sensor (often integrated into the DEF Head Unit) to the DCU for chafing, breaks, or an open circuit.

2. 2

   Disconnect the DEF sensor and inspect the pins for corrosion, bent terminals, or moisture intrusion.

3. 3

   Verify the sensor supply voltage and ground at the connector. Check for a short circuit to ground or an open circuit on the sensor pins.

4. 4

   Test the SAE J1939 CAN communication lines between the sensor and the DCU to ensure data messages can be transmitted.

5. 5

   Check for accompanying codes (such as P205A for DEF temperature or P206A for DEF quality). If multiple sensor values are missing, the entire integrated DEF Head Unit has likely failed.

1. 1

   Park machine and disconnect battery

   Park the machine on a hard, level surface, turn off the engine, and disconnect the battery to prevent electrical shorts.

2. 2

   Clean DEF tank area

   Locate the DEF tank and thoroughly clean the area around the top of the tank where the sensor mounts to prevent dirt and debris from falling into the DEF fluid.

3. 3

   Disconnect electrical connector

   Disconnect the electrical wiring harness connector from the DEF tank level sensor assembly.

4. 4

   Disconnect fluid lines

   Carefully disconnect the DEF suction and return fluid lines from the top of the sensor unit.

5. 5

   Remove retaining hardware

   Remove the retaining ring or mounting bolts securing the sensor assembly to the DEF tank.

6. 6

   Extract old sensor

   Carefully extract the old DEF sensor/head unit assembly from the tank.

7. 7

   Install new sensor

   Install the new DEF tank level sensor, ensuring the rubber O-ring or gasket is properly seated to prevent fluid leaks or contamination.

8. 8

   Secure sensor

   Secure the sensor with the retaining ring or bolts.

9. 9

   Reconnect lines and connector

   Reconnect the DEF fluid lines and the electrical connector.

10. 10

    Reconnect battery

    Reconnect the battery and turn the ignition on.

11. 11

    Clear fault codes

    Use a diagnostic tool (such as the CNH Electronic Service Tool) to clear the DCU 19649 / P203A fault codes.

12. 12

    Verify DEF level

    Verify that the DEF level is now reading correctly on the machine's instrument cluster.