New Holland DCU 19650 – DCU (Dosing Control Unit): UREA Tank level error (CAN message or electrical with real sensor) — Level over CAN: SAE J1939 Signal Not in Range Level sensor connected directly: SRC high — P203D Reagent - tank level sensor - short circuit high

This code indicates that the Dosing Control Unit is receiving a voltage signal from the Diesel Exhaust Fluid (DEF/Urea) tank level sensor that is higher than the maximum expected threshold (short circuit high). Because the signal is out of range, the system cannot accurately determine how much DEF is in the tank, which can lead to emissions non-compliance, warning messages, and eventual engine power derate.

• T5 series
• T6 series
• T7 series
• T8 series
• T9 series
• CR series combines
• CX series combines
• FR forage harvesters
• Backhoe loaders
• Wheel loaders
• Skid steers

1. 1

   Visually inspect the DEF tank, the DEF header unit, and the wiring harness for physical damage, corrosion, or DEF crystallization/contamination at the connectors.

2. 2

   Manually verify the actual DEF fluid level in the tank to rule out an empty tank or frozen fluid causing erratic sensor behavior.

3. 3

   Disconnect the sensor and turn the key to the ON position (engine OFF). Backprobe the sensor connector and measure the DC voltage at the signal pin relative to ground. Check the reference voltage (typically 5V) and the ground circuit.

4. 4

   Perform continuity checks between the sensor connector and the DCU harness connector. Specifically, test for a short to battery voltage (which triggers the circuit high condition) or an open circuit in the wiring harness.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent electrical spikes during repair.

2. 2

   Harness Repair (If Applicable)

   If the multimeter tests reveal a short to voltage or a damaged connector in the wiring harness, repair or replace the affected wiring segment.

3. 3

   Sensor Replacement (If Harness is Good)

   If the wiring tests perfectly, the internal circuitry of the DEF level sensor has failed and the sensor assembly must be replaced.

4. 4

   Remove the DEF Header

   Clean the area around the top of the DEF tank to prevent dirt from falling in. Disconnect the electrical connector, the DEF suction and return lines, and the coolant lines (if equipped with a heated header).

5. 5

   Extract and Install

   Unbolt the DEF header/sensor assembly and pull it straight up out of the tank. Insert the new OEM DEF level sensor assembly, ensuring the tank seal/O-ring is properly seated.

6. 6

   Reassembly

   Reconnect the coolant lines, DEF fluid lines, and the electrical connector.

7. 7

   Clear Codes

   Reconnect the battery, connect a diagnostic scan tool (like the CNH Electronic Service Tool), clear the DCU 19650 / P203D fault codes, and cycle the key to verify the DEF level is reading accurately and the code does not return.