New Holland DCU 19334 – DCU (Dosing Control Unit): System frozen and not free in time _Defreezing Mode and Detection Errors (Inlet line defreezing failed) _P20C2 Reagent -suction tube heating -detection mode of heating

The DEF (Diesel Exhaust Fluid / AdBlue) suction line heater failed to thaw the fluid in the inlet line within the required time limit.

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1. 1

   Inspect the wiring harness and connectors between the DCU and the DEF suction line heater for damage, corrosion, or loose pins

2. 2

   Check for any damaged or loose machine grounds

3. 3

   Test the DEF suction line heater relay (Relay 5 or C-R5) for a short to ground, short to battery, or open circuit

4. 4

   Test the resistance of the DEF suction line heater element to ensure it is not internally open or shorted

5. 5

   Check for scale build-up (white deposits) in the DEF tank or lines that might restrict flow and affect thawing

1. 1

   Stop the engine and let it cool before starting work.

   Do not start the engine during the service procedures.

2. 2

   Repair or replace the affected harness sections.

   If diagnostic checks reveal damaged wiring or corroded connector pins in the DEF suction line heater circuit.

3. 3

   Replace the relay in the fuse panel.

   If the DEF heater relay fails testing.

4. 4

   Replace the DEF suction line.

   If the suction line heater element itself is open or shorted.

5. 5

   Install a repair clip instead of replacing the entire line.

   If the issue is a broken retaining ear on the 90-degree male DEF suction line fitting.

6. 6

   Clear the fault codes using a diagnostic tool and run a DEF system prime/heater test to verify the repair.

   Once repairs are made.