Case IH 19335 – DCU: System frozen and not free in time | Defreezing Mode and Detection Errors (pressure line defreezing failed) | P20BE Reagent -pressure tube heating -detection mode of heating

The Diesel Exhaust Fluid (DEF / Reagent) pressure line failed to thaw within the expected time frame during cold weather operation due to a malfunction in the pressure tube's heating circuit, which can be caused by an open circuit, a short to ground, a short to battery, or a burned-out heating element.

• Tier 4a
• Tier 4
• Tier 4B
• Tier 4 Final
• Steiger (350, 400, 435, 450, 500, 550, 600)
• Quadtrac and Rowtrac (350-600)
• Magnum (235-340 Series 4)
• Puma
• MX Series

1. 1

   Inspect the DEF pressure line heater relay for an open circuit, short to ground, or short to battery.

2. 2

   Check the electrical connectors on the DEF pressure line for corrosion, moisture, or physical damage.

3. 3

   Test the DEF pressure line heating element for continuity and proper resistance to rule out a burned-out element (open load) or a short circuit.

4. 4

   Verify that the DCU is receiving proper battery voltage to command the heating cycle.

1. 1

   Turn off the machine and disconnect the battery to prevent electrical shorts.

   If the heating element inside the line has failed, the entire line must be replaced, as the heater is integrated into the hose.

2. 2

   Locate the DEF pressure line running between the DEF pump/supply module and the dosing injector.

3. 3

   Disconnect the electrical harness connectors for the pressure line heater.

4. 4

   Disconnect the fluid fittings at both ends of the DEF pressure line.

   Have a catch pan ready for any residual DEF fluid.

5. 5

   Remove the faulty DEF pressure line and route the new line in the exact same position.

   This prevents chafing or proximity to extreme exhaust heat.

6. 6

   Reconnect the fluid fittings and the electrical connectors.

7. 7

   If diagnostics pointed to a faulty relay, replace the DEF pressure line heater relay in the fuse/relay box.

8. 8

   Reconnect the battery, clear the fault codes from the DCU, and run a DEF system heater test or dosing test via a diagnostic tool to verify the repair.