Case IH 19255 (F-4354-05) - ECU – Engine Control Unit (ECU) or Dosing Control Unit (DCU) / Aftertreatment Control Module: DEF / Urea pressure line heater control circuit open circuit

The system has detected a break in the electrical circuit (open load) for the heater that wraps around the Diesel Exhaust Fluid (DEF) pressure line. Because the circuit is open, the heater cannot operate, which will eventually trigger an emissions inducement (engine derate).

• VESTRUM CVX
• Puma
• Magnum
• Steiger
• Optum
• SV216D
• T7
• T8
• T9

1. 1

   Visually inspect the DEF pressure line heater electrical connector for corrosion, backed-out pins, moisture, or physical damage.

2. 2

   Check the wiring harness continuity between the ECU/DCU and the DEF pressure line heater connector for chafed, broken, or disconnected wires.

3. 3

   Verify the battery supply and test the DEF heater main relay to ensure power is actually being sent to the circuit.

4. 4

   Using a multimeter, measure the resistance across the pins of the DEF pressure line heater element itself. If the multimeter reads 'OL' (Open Loop) or infinite resistance, the heating element inside the line has failed.

1. 1

   Preparation

   Turn off the machine, allow the exhaust and engine to cool completely, and disconnect the battery.

2. 2

   Locate the Line

   Trace the DEF pressure line routing. It runs from the DEF supply module (pump) to the DEF dosing injector located on the exhaust SCR catalyst.

3. 3

   Disconnect Electricals

   Unplug the electrical connector for the pressure line heater.

4. 4

   Remove the Line

   Disconnect the fluid fittings at both the DEF pump and the dosing injector. Have a clean catch pan ready, as residual DEF will spill. Cap the open ports immediately to prevent contamination.

5. 5

   Install the New Line

   Route the new DEF pressure line exactly as the original was routed. Proper routing is critical to prevent the new line from chafing against the chassis or melting against hot exhaust components.

6. 6

   Reconnect

   Secure the fluid fittings and plug in the new heater electrical connector.

7. 7

   Clear Codes and Reset

   Reconnect the battery and turn on the ignition. Use the Case IH Electronic Service Tool (EST) to clear the fault codes. Because this fault causes an emissions inducement, you must perform the 'Inducement Unlock / Counter Reset' procedure in the diagnostic software once the repair is finished.