Case IH 19307 – DCU (Dosing Control Unit): UREA pressure too high

The system's pressure sensor is reading a Diesel Exhaust Fluid (DEF/Urea) pressure that exceeds the maximum allowable limit. This usually points to a physical blockage in the DEF delivery line, a clogged dosing injector (due to urea crystallization), or a failed pressure sensor.

• Tier 4a
• Tier 4b
• Case IH Magnum Tractors: 235, 260, 290, 315, 340 (Series 4)
• Case IH Steiger & Quadtrac Tractors: 350, 400, 450, 500, 550, 600 (NA and QT NA models)
• Case IH Rowtrac Tractors: 350, 400, 450, 500
• Case IH Puma Tractors
• Case IH Combines: 8230, 9230

1. 1

   Inspect the DEF pressure line running from the DEF pump to the dosing injector for any kinks, pinching, or physical damage that could restrict flow.

2. 2

   Remove the DEF dosing valve/injector and inspect the nozzle for white crystalline buildup (urea crystallization).

3. 3

   Use the dealer Electronic Service Tool (EST) to perform a Urea Dosing System Test (UDST) and monitor live pressure data.

4. 4

   Check if the pressure reads implausibly high even when the pump is off, which indicates the pressure sensor (integrated into the DEF supply module) has failed.

1. 1

   Depressurize and Disconnect

   Turn off the machine, disconnect the battery, and allow the DEF system to purge/depressurize.

2. 2

   Clean the Dosing Injector

   If crystallization was found during diagnostics, clean the DEF dosing injector and the mounting port using warm water (urea dissolves easily in warm water). Do not use harsh chemicals or wire brushes that could damage the nozzle.

3. 3

   Flush the Lines

   Flush the DEF pressure line with warm water or blow it out with compressed air to ensure no blockages remain in the line.

4. 4

   Replace the DEF Pump Module

   If the lines and injector are completely clear but the code persists (or if the EST showed a failed pressure sensor reading), the internal pressure sensor in the DEF pump module has failed. You must replace the entire DEF Urea Injection Module.

5. 5

   Reassemble and Calibrate

   Install the new pump module or cleaned injector. Reconnect the battery.

6. 6

   Clear Codes and Test

   Use the EST to clear the 19307 / P204B fault code. Run a stationary regeneration or a UDST to verify that the DEF pressure now regulates correctly between 71.1 and 89.9 psi.