Case IH 19703 – Engine Control Module (ECM) or Dosing Control Unit (DCU): Supply module heater temperature sensor is not working correctly.

The control module is receiving an out-of-range electrical signal (duty cycle) from the temperature sensor located inside the DEF supply module's heating circuit. This sensor monitors the temperature of the DEF fluid to prevent freezing and ensure proper dosing. When it fails, the system cannot accurately regulate the DEF heater.

• Tier 4b
• Tier 4 equipment
• Stage V equipment
• Magnum series (180, 190, 210, 225, 235, 260, 290, 340, 370)
• Steiger series (350, 400, 450, 500, 550, 600)
• Puma series (130 to 240)
• Maxxum series (110 to 140)
• Farmall series (95A, 100C, 110C)
• Axial-Flow series (5130, 6130, 7130, 7230, 8230, 9230)
• Patriot series (4430)
• Titan series

1. 1

   Turn off the ignition switch and wait until communication with the diagnostic scan tool is fully discontinued to ensure the ECM has powered down and saved data.

2. 2

   Inspect the DEF supply module for external damage, leaks, or crystallized urea (white crust).

3. 3

   Inspect the wiring harness and connectors between the DEF Supply Module and the ECM/DCU for corrosion, bent pins, or wire chafing that could cause an out-of-range duty cycle signal.

4. 4

   Use the Case IH Electronic Service Tool (EST) or a Bosch KTS diagnostic tool to run a Denoxtronic DEF system test (dosing and supply quantity test) and monitor live data from the heater temperature sensor.

1. 1

   Disconnect battery

   Disconnect the machine's battery ground cable.

2. 2

   Clean area

   Locate the DEF Supply Module. Ensure the surrounding area is completely clean of dried white urea crust and dust. If necessary, flush the external housing face with clean distilled water only to safeguard the internal high-pressure fluid loops.

3. 3

   Disconnect harness

   Carefully disconnect the electrical harness connectors from the supply module.

4. 4

   Disconnect fluid lines

   Disconnect the DEF fluid lines (suction, pressure, and backflow). Cap the lines immediately to prevent contamination.

5. 5

   Remove module

   Unbolt the DEF supply module from its mounting bracket and remove the unit.

6. 6

   Install module

   Install the new or remanufactured DEF supply module into the bracket.

7. 7

   Reconnect lines and harness

   Reconnect the DEF fluid lines and the electrical harness.

8. 8

   Reconnect battery

   Reconnect the battery ground.

9. 9

   Verify repair

   Connect the Case IH EST diagnostic tool, clear the 19703 fault code, and run a system prime/dosing test to verify the repair and ensure there are no leaks.