Case IH 19102 – DCU (Dosing Control Unit): UREA level sensor (electrical) | signal low | Reagent - tank level sensor - short circuit low.

The voltage signal coming from the Diesel Exhaust Fluid (DEF / Urea) tank level sensor has dropped below the minimum acceptable threshold, indicating a short circuit to a low voltage source (ground) either within the sensor itself or in the wiring harness.

• Tier 4a
• Case IH Steiger (350, 400, 450, 500, 550, 600)
• Case IH Quadtrac and Rowtrac series
• Case IH Magnum (235–340 Series 4)
• Case IH Puma series
• Case IH Farmall series

1. 1

   Inspect the wiring harness leading to the DEF tank header unit for chafing, melting, or pinched wires rubbing against the chassis that could cause a short to ground.

2. 2

   Disconnect the DEF level sensor connector at the tank and inspect the pins for corrosion, moisture, or DEF crystallization, which can bridge pins and cause a short.

3. 3

   Isolate the short: With the sensor disconnected, turn the key on and check active fault codes. If the code changes to an open circuit or signal high (e.g., 19101 / P203D), the short is internal to the DEF header unit. If it remains short circuit low, the short is in the machine's wiring harness.

4. 4

   Use an Electronic Service Tool (EST) to monitor the live voltage data of the DEF level sensor to verify the low signal reading.

1. 1

   Repair wiring harness

   If the diagnostic checks point to a wiring issue, locate the short to ground in the harness, repair the damaged wire, and secure it away from vibration or heat sources.

2. 2

   Clean DEF tank area

   If the DEF header unit is internally shorted, the assembly must be replaced. Begin by thoroughly cleaning the area around the top of the DEF tank to prevent dirt or debris from falling into the tank.

3. 3

   Drain DEF tank

   Drain the DEF tank if necessary, or ensure the fluid level is below the mounting flange.

4. 4

   Disconnect DEF header unit

   Disconnect the electrical connector and the DEF supply/return lines from the top of the DEF header unit.

5. 5

   Remove mounting hardware

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

6. 6

   Remove old DEF header unit

   Carefully pull the old DEF header unit (which houses the level sensor, temperature sensor, and fluid pickup tubes) out of the tank.

7. 7

   Install new DEF header unit

   Install the new DEF header unit using a new O-ring or gasket to ensure a proper seal and prevent leaks.

8. 8

   Reinstall hardware and reconnect

   Reinstall the mounting hardware, and reconnect the DEF lines and electrical connector.

9. 9

   Refill DEF tank

   Refill the tank with fresh, uncontaminated Diesel Exhaust Fluid.

10. 10

    Clear fault code and verify

    Use a diagnostic tool (EST) to clear the 19102 / P203C fault code and verify that the DEF level is reading accurately on the machine's display.