Case IH 19754 – After-Treatment Control Module (ACM) / Dosing Control Unit (DCU) / Engine Control Module (ECM / EEM4): Ratio between DEF/AdBlue Pump Speed and Dosing Valve exceeded

This fault indicates an abnormal relationship between the speed of the DEF (Diesel Exhaust Fluid) pump and the pressure or flow at the dosing valve. The system monitors the pump's RPMs against the pressure it generates. If the pump speed is too high for a given pressure, it typically means the pump is sucking in air, there is an internal leak, or the dosing valve is stuck open/leaking. Conversely, if the pump speed is too low or erratic, it may indicate a restriction, a faulty pressure sensor, or that an incorrect dosing valve version is installed, causing a communication mismatch.

• Tier 4b
• Case IH Axial-Flow combines (7230, 9230)
• high-horsepower tractors

1. 1

   Visual Inspection for Leaks: Check the DEF dosing valve, pump, and lines for external leaks, which will appear as a white, crystallized urea powder buildup.

2. 2

   Pressure Test: Verify the DEF system pressure using a diagnostic tool. If the pump cannot reach the target pressure (often around 140 psi), it may be overspeeding to compensate, pointing to a failed pressure sensor or a leaking dosing valve.

3. 3

   Air Intrusion Check: Check for air being sucked into the DEF lines upstream of the pump.

4. 4

   Dosing Quantity Test: Perform a DEF dosing rate test using a diagnostic tool and a measuring cup to verify the dosing valve's output volume (e.g., some systems specify a tolerance of 165–202 ml during the test routine).

5. 5

   Part Number Verification: Verify the correct dosing valve part number is installed. Mismatched versions (e.g., UL2.0 vs. UL2.2 dosers) send different CAN messages and will immediately trigger a DEF pump speed fault.

6. 6

   Fluid Quality Check: Check DEF fluid quality for contamination (diesel, oil, hard water) or improper concentration, which can cause internal pump abrasion or crystallization.

1. 1

   Depressurize the System

   Ensure the machine is turned off and allow the ACM's delayed reverting/draining strategy to pump the DEF back into the tank and depressurize the lines.

2. 2

   Clean the Area

   Clean any spilled or crystallized DEF around the fittings using hot water and a clean, lint-free cloth. Do not use high-pressure washers on the dosing components.

3. 3

   Disconnect Components

   Disconnect the hydraulic (DEF) lines first, followed by the electrical connectors. This prevents DEF fluid from accidentally entering and damaging the electrical pins.

4. 4

   Replace the Faulty Component

   If the dosing valve is constantly dripping, leaking, or failed the quantity test, replace the DEF Dosing Valve. If the dosing valve is fine but the pump has an internal leak or cannot build pressure, replace the DEF Pump (Supply Module).

5. 5

   System Maintenance

   If replacing the DEF pump, OEM guidelines require cleaning the DEF tank and replacing the main DEF filter.

6. 6

   Verification

   Reconnect all lines and harnesses. Use a diagnostic scan tool to clear the fault codes and perform an SCR system self-check (SCR-ADS test) or a forced regeneration to verify the repair and ensure the pump speed and pressure ratio have normalized.