Case IH 19379 – DCU: UREA Temperature too low during commissioning | Temperatures not plausible during commissioning

During the system startup (commissioning) phase, the temperature reading from the Diesel Exhaust Fluid (DEF / Urea) tank temperature sensor is abnormally low or implausible compared to expected environmental conditions.

• Tier 4a
• Tier 4 / Tier 4B Case IH and New Holland agricultural equipment
• Magnum series (235, 250, 280, 310, 340, 380)
• Steiger and Rowtrac series (350, 400, 450, 500, 550, 600)
• Puma series tractors
• Maxxum series tractors
• Axial-Flow Combines (7230, 8230, 9230, 7240, 8250)

1. 1

   Use the Electronic Service Tool (EST) to monitor the raw diagnostic values of the UREA temperature sensor. Compare the reading to the actual ambient temperature on a cold engine; if the reading is implausible, the sensor is likely at fault.

2. 2

   Inspect the wiring harness and electrical connector at the DEF tank header unit for corrosion, short circuits, or open circuits (which can cause voltage to drop and read as a low temperature).

3. 3

   Check for related DCU fault codes that might indicate a broader sensor failure, such as 19514 (Urea tank temperature sensor out of range) or 19415 (Empty UREA tank).

4. 4

   Verify that the DEF fluid itself is not degraded or frozen, as poor fluid quality or extreme environmental conditions can sometimes trigger plausibility errors.

1. 1

   Disconnect battery

   Disconnect the machine's battery to prevent electrical shorts and ensure the DCU is powered down.

2. 2

   Clean DEF tank area

   Clean the area around the top of the DEF tank to prevent dirt or debris from contaminating the DEF fluid.

3. 3

   Disconnect electrical harness

   Disconnect the main chassis electrical harness connector from the DEF Head Unit.

4. 4

   Disconnect fluid lines

   Carefully disconnect the DEF supply and return lines from the header.

5. 5

   Remove mounting hardware

   Remove the mounting hardware and the old DEF tank mounting seal.

6. 6

   Extract DEF Head Unit

   Extract the faulty DEF Head Unit from the tank.

7. 7

   Install new DEF Head Unit

   Install the new DEF Head Unit using a new mounting seal to prevent leaks.

8. 8

   Reconnect lines and connector

   Reconnect the DEF fluid lines and the electrical connector.

9. 9

   Clear fault code and verify

   Reconnect the battery, turn the key on, and use the Electronic Service Tool (EST) to clear the 19379 fault code and verify that the new temperature readings are plausible.