Case IH 4374 – Engine Control Module (ECM), Aftertreatment Control Module (ACM), or Dosing Control Unit (DCU): DEF pump motor speed permanent deviation or pressure stabilization error at the SCR dosing valve

The Dosing Control Unit detects an abnormal motor speed signal from the DEF pump, meaning the pump is either not available for actuation, is running at the wrong speed, or is failing to build/stabilize pressure in the emissions system.

• Steiger T4B
• Magnum
• Steiger
• Puma
• Maxxum
• Steiger 620

1. 1

   Check ambient conditions to verify if the tractor has been sitting in freezing temperatures, which can freeze the DEF/reagent and trigger the code sporadically.

2. 2

   Inspect the harness connectors on the metering side of the DEF pump for a short to ground, short to battery, or an open circuit.

3. 3

   Run a diagnostic test to see if the DEF pump is actually delivering fluid to rule out a sporadic glitch.

1. 1

   Thaw and Clear

   If operating in freezing conditions, allow the DEF tank and lines to thaw completely. Clear the code and cycle the key to see if the fault returns.

2. 2

   Repair Wiring

   If the harness inspection reveals damaged wires or corroded connectors at the DEF pump motor, repair the connections and re-test the system.

3. 3

   Replace the Pump Module

   If the fault code 4374 appears several times permanently and the pump is not delivering fluid, replace the DEF pump module.