Case IH 19155 – DCU: DEF/AdBlue Supply Module Pump Motor Speed Deviation

The engine's control system has commanded the DEF pump motor to run at a specific duty cycle, but the internal RPM measurement of the pump is deviating from the expected speed. This is typically caused by an electrical fault preventing proper voltage or a physical blockage (severe DEF crystallization/freezing) blocking the pump motor.

• Tier 4a
• Tier 4b
• Magnum (180-370)
• Steiger (350-600)
• Puma (130-240)
• Maxxum (110-150)
• Farmall (95A, 100C, 110C, 115U, 130A, 140A)
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Patriot 2250
• Patriot 3240
• Patriot 3340
• Patriot 4430
• Titan series
• Farmlift Telehandlers
• Wheel Loaders (521F, 821F)

1. 1

   Stop the engine and let the exhaust system cool completely before working on the DEF system

2. 2

   Check for damaged or loose machine grounds and connector pins at the DEF Supply Module, looking closely for debris or water inside the terminals

3. 3

   Inspect the control circuit between the DEF supply module and the DCU for an open circuit or a short to ground/battery

4. 4

   Inspect the DEF tank suction tubes for cracks or air leaks that can cause the pump to lose prime

5. 5

   Use a diagnostic scan tool to run a Reductant Pump Motor Functional Check to see if the internal RPM measurement matches the command

1. 1

   Power down DCU

   Turn off the ignition switch and wait until all communication with the diagnostic scan tool is discontinued to ensure the DCU is powered down.

2. 2

   Drain or isolate DEF tank

   Drain or isolate the DEF tank (depending on if the pump is tank-mounted or frame-mounted) to prevent fluid loss.

3. 3

   Disconnect harness and lines

   Disconnect the electrical harness and the heated DEF lines from the supply module. Note: DEF is highly corrosive; clean any spills immediately with warm water.

4. 4

   Remove DEF Supply Module

   Remove the DEF Supply Module. If it is a tank-mounted flange assembly, unbolt it from the top of the tank. If it is a remote doser pump, unbolt it from the frame bracket.

5. 5

   Inspect and clean filter

   Before replacing the whole pump, check the DEF pump filter element. If it is heavily crystallized, replacing the filter and cleaning the module with warm distilled water may unblock the motor.

6. 6

   Install new module

   If the motor is dead, install the replacement DEF Supply Module. Reconnect the DEF lines and electrical harness.

7. 7

   Program new module

   Connect your diagnostic scan tool. A new DEF Supply Module must be programmed/calibrated to the vehicle's DCU after replacement.

8. 8

   Clear codes and test

   Clear DTC 19155 / P208A, turn on the ignition, and run a functional test to verify the pump builds pressure (typically up to 9 bar / 130 psi) without speed deviation.