Case IH 19084 (DTC 5E5A) - ECU – DCU (Dosing Control Unit): DEF/AdBlue reverting valve driver circuit open failure

The reverting valve (a 4-2 way valve) is a critical component of the Bosch Denoxtronic DEF supply module. It is responsible for reversing the flow of the DEF/AdBlue fluid to purge the lines of fluid when the machine is shut down, preventing the fluid from freezing and expanding inside the lines. The code triggers when the control unit detects an open circuit, high resistance, or a short in the power supply circuit driving this valve.

• MAXXUM T4E
• 240 Series Axial-Flow (7240, 8240, 9240)
• 130 and 230 Series (7130, 7230, etc.)
• Magnum Series (e.g., 235–340 Series 4)
• Steiger Series
• Maxxum
• Puma
• Patriot Series (e.g., 4430, 4450)

1. 1

   Visual Inspection: Check the wiring harness and connectors between the DCU and the DEF Supply Module. Look for water intrusion, corrosion, or adhering foreign material (like dried white urea crust) on the terminals.

2. 2

   Circuit Testing: Use a multimeter to test the reverting valve power supply circuit (UB3) for an open circuit, high resistance, or a short to ground/battery.

3. 3

   Component Testing: Check the internal resistance of the reverting valve coil at the DEF supply module connector to determine if the valve itself has failed internally (open load).

1. 1

   Turn off ignition and disconnect battery

   Turn off the ignition switch and disconnect the battery to prevent electrical spikes.

2. 2

   Disconnect electrical harness

   Disconnect the electrical harness at the DEF Supply Module.

3. 3

   Clean connector area

   Thoroughly clean the connector area. If flushing the external housing face, use only clean distilled water to safeguard the internal high-pressure fluid loops from contamination.

4. 4

   Repair wiring and pins

   If the diagnostic tests reveal damaged wiring, repair the open/shorted wire in the urea fluid reverting valve power supply circuit and replace any corroded connector pins.

5. 5

   Replace DEF Supply Module if valve is faulty

   If the wiring is intact but the reverting valve coil is open or shorted, the valve cannot be serviced separately. You must replace the entire DEF Supply Module.

6. 6

   Install new DEF Supply Module

   Install the new DEF Supply Module. Ensure the DEF lines are seated correctly and not blocked.

7. 7

   Reconnect battery and clear DTC

   Reconnect the battery, turn the ignition ON (without starting the engine), and use a diagnostic scan tool to clear the DTC.

8. 8

   Verify repair

   Cycle the key and run the machine to verify the code does not return and that the system builds pressure normally.