New Holland DCU 19335 – DCU (Dosing Control Unit): System frozen and not free in time | Defreezing Mode and Detection Errors (pressure line defreezing failed)

This code indicates a failure in the Selective Catalytic Reduction (SCR) system's defrosting sequence. The DEF pressure line heater fails to thaw the fluid within the allotted time limit, or the system detects an electrical fault (open circuit, short to ground, or short to battery) in the pressure line's heating circuit.

• New Holland T7 Series (T7.220, T7.235, T7.250, T7.260, T7.270)
• New Holland T8 Series
• New Holland T9 Series

1. 1

   Check Battery and Relay Supply: Verify the battery supply voltage into the main relay and the DEF pressure line heater connector.

2. 2

   Inspect the Wiring Harness: Inspect the wiring harness between the DCU and the DEF pressure line heater for chafing, breaks, or corrosion. Look specifically for an open circuit (P20BE-13) or a short to battery/ground.

3. 3

   Test the Heater Relay: Test the DEF line heater relay to ensure it is properly switching power to the pressure line when commanded by the DCU.

4. 4

   Check DCU Connections: Inspect the main connector at the Dosing Control Unit (DCU) for pushed pins, moisture intrusion, or corrosion.

5. 5

   Measure Heater Resistance: Disconnect the DEF pressure line and use a multimeter to measure the resistance across the integrated heater element pins. If the circuit is open (infinite resistance) or shorted, the line itself has failed.

1. 1

   Power Down

   Turn off the machine and turn off the battery disconnect switch. Ensure the SCR system has completed its purge cycle before disconnecting any batteries.

2. 2

   Access the DEF Lines

   Locate the DEF pump/supply module and trace the DEF pressure line (the line carrying fluid from the pump to the dosing injector on the exhaust).

3. 3

   Disconnect Electrical and Fluid Fittings

   Unplug the electrical connector for the pressure line heater. Depress the release tabs on the quick-connect fluid fittings at both the pump module and the dosing injector to remove the line. Note: Have a catch pan ready, as residual DEF may spill.

4. 4

   Install the New Line

   Route the new DEF pressure line exactly as the old one was routed. Ensure it is not pinched or resting against high-heat exhaust components. Click the fluid fittings into place and reconnect the heater electrical plug.

5. 5

   Clear Codes and Reset Inducement

   Use a diagnostic tool (such as the CNH Electronic Service Tool) to clear the fault codes and perform an 'Inducement Unlock / Counter Reset'.

6. 6

   System Test

   Turn the key switch to the ON position. The system will perform an electrical connectivity check. Start the engine and monitor the DCU to ensure the heater circuit is operating without throwing a new P20BE code.