New Holland 19650 – DCU: Urea Tank Level Error

The Dosing Control Unit (DCU) has received a signal from the urea (DEF) tank level sensor that is outside of its expected range, specifically indicating a short circuit high condition where voltage exceeds the maximum allowable limit. This fault corresponds to the generic SAE code P203D. Because the system cannot accurately determine the DEF level, it can compromise the Selective Catalytic Reduction (SCR) emissions system, leading to check engine lights, DEF warnings, engine derate, or a countdown to a no-start condition.

• T6.120-180 Dual/Electro Control
• T6.125
• T6.145
• T6.155
• T6.165
• T6.175
• T7.230
• T7.260
• T7.270
• T7.275
• T7.290
• T7.315
• T8.275
• T8.320
• T8.350
• T8.410
• T9.565
• T9.600
• T9.645
• T9.700

1. 1

   Verify the DEF tank is adequately filled and fluid quality is within the acceptable range of 31.8% to 33.2% urea concentration using a refractometer

2. 2

   Inspect the DEF injector, lines, and tank for any signs of crystallization, which can clog the system

3. 3

   Inspect the urea level sensor's connector and wiring harness for damage, corrosion, loose connections, or withdrawn pins

4. 4

   Using a digital multimeter (DMM), inspect the sensor's signal circuit and ground circuit for open circuits, high resistance, or shorts to a power source

5. 5

   Clear fault codes and operate the vehicle to see if the code reappears

1. 1

   Connect a Diagnostic Tool

   Connect a diagnostic tool, such as Jaltest, to the vehicle to read and confirm the fault codes.

2. 2

   Perform Initial Checks

   Carry out the diagnostic checks listed above.

3. 3

   Address Wiring Issues

   If any wiring issues like open circuits, shorts, or damaged connectors are found, repair or replace the affected sections of the harness.

4. 4

   Replace the Sensor

   If the diagnostic checks point to a faulty sensor, it will need to be replaced. The DEF tank level sensor is often part of a larger assembly, sometimes called the 'DEF header,' which may also include the temperature sensor, quality sensor, and heating element.

5. 5

   System Verification

   After replacing the sensor, it is crucial to perform a system verification or reset. This may require a specific procedure using a diagnostic tool to inform the control unit of the new component and verify the correct operation of the SCR system.