Case IH 19654 – DCU (Dosing Control Unit): UREA Tank level error (CAN message or electrical with real sensor) – Level over CAN: SAE J1939 Erroneous Signal Level sensor connected directly: SRC low – P203A Reagent - tank level sensor - Open circuit

The controller is not receiving a valid electrical signal from the Diesel Exhaust Fluid (DEF / Urea) tank level sensor. The 'SRC low' and 'Open circuit' designations indicate a physical break in the wiring, a disconnected plug, or a completely failed internal sensor circuit.

• Tier 4a
• Magnum
• Steiger
• Puma
• Luxxum
• Axial-Flow 7230
• Axial-Flow 8230

1. 1

   Check the wiring harness running from the DEF tank header unit to the DCU for chafing, rodent damage, or broken wires.

2. 2

   Disconnect the electrical plug at the DEF header and inspect the pins for corrosion, moisture intrusion, or bent terminals.

3. 3

   Check if other DEF codes are present (such as temperature sensor codes); if multiple sensor codes appear simultaneously, the entire header unit has likely failed.

1. 1

   Prepare machine

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Clean area

   Locate the DEF tank. Thoroughly clean the top of the tank and the area around the DEF header unit to prevent dirt and debris from falling into the tank during removal.

3. 3

   Disconnect electrical harness

   Disconnect the electrical harness connector from the DEF header.

4. 4

   Disconnect fluid lines

   Disconnect the DEF suction and return lines from the header. Cap the lines immediately to prevent contamination.

5. 5

   Remove mounting hardware

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

6. 6

   Remove DEF header

   Carefully pull the DEF header assembly straight up and out of the tank.

7. 7

   Install new DEF header

   Install the new DEF header unit, ensuring the new O-ring or sealing gasket is properly seated to prevent leaks.

8. 8

   Reinstall mounting hardware

   Reinstall the retaining ring or bolts.

9. 9

   Reconnect lines and harness

   Reconnect the DEF fluid lines and the electrical connector.

10. 10

    Clear fault codes

    Reconnect the battery, turn the key on, and use a diagnostic tool to clear the fault codes.