Case IH 19756 – Engine Control Module (ECM) or Aftertreatment Control Module (ACM) / Dosing Control Unit (DCU): Ratio between DEF/AdBlue Pump Speed and Dosing Valve exceeded

The DEF supply pump is running at a speed that is too high relative to the amount of fluid being commanded through the dosing valve, failing to build or maintain the expected 9 bar (130 psi) of pressure.

• Tier 4b
• Puma 150
• Farmall 110A
• Farmall 120A
• Farmall 130A
• Farmall 140A
• Maxxum 115
• Magnum 180
• Magnum 200
• Magnum 220
• Magnum 240
• Magnum 250
• Combine 5140
• Combine 6150
• Combine 7150
• Combine 9230
• Patriot 2250
• Patriot 3240
• Patriot 3340

1. 1

   Check for air leaks in the suction line, specifically looking for a hairline crack at the top of the suction tube inside the DEF tank unit assembly.

2. 2

   Inspect all DEF lines and connectors between the pump and the dosing valve for external leaks, crimps, or damage.

3. 3

   Check the DEF pump filter for clogs that could starve the suction side of the pump.

4. 4

   Perform a DEF pressure test using OEM diagnostic software (e.g., Easy Engine or SerDia) with the engine stopped (should regulate and hold at exactly 9 bar / 130 psi).

5. 5

   Perform a Dosing Valve Test ('Urea Dosing Valve Check' or 'Dosing Valve Solenoid test') via the diagnostic tool to verify the valve is not stuck open and bleeding off pressure.

6. 6

   Verify the thawing system to ensure DEF lines, pump, and tank are not frozen, and check the DEF heater control valve.

1. 1

   Cool Down

   Stop the engine and let the exhaust and coolant systems cool completely before servicing the DEF system.

2. 2

   Resolve Suction/Leak Issues

   If the diagnostic checks reveal a cracked suction tube in the tank, replace the DEF tank sending unit assembly. If external lines are leaking, replace the affected lines.

3. 3

   Replace the Filter

   If the DEF pump filter is clogged, replace it and re-prime the system.

4. 4

   Replace the Dosing Valve

   If the dosing valve failed the diagnostic test (stuck open or leaking), remove it from the exhaust pipe, clean the mounting boss, and install a new dosing valve.

5. 5

   Replace the DEF Pump (Supply Module)

   If there are no leaks, the filter is clean, the dosing valve is functioning, and the pump still cannot maintain 9 bar pressure, the internal pump mechanism has failed. Remove the DEF pump/supply module and install a replacement.

6. 6

   Programming

   A new Bosch DEF pump/supply module must be programmed/calibrated to the vehicle's ECU using the OEM diagnostic tool after replacement.

7. 7

   Verification

   Clear the fault codes and run an SCR catalyst-free burn or system test to verify the repair.