Case IH 19182 – DCU (Dosing Control Unit): Reverting valve (4-2way valve) electrically | Short circuit to ground | P20A2 Vent valve (Reductant Purge Control Valve) - short circuit low

The system has detected a short circuit to ground in the electrical circuit of the DEF (Diesel Exhaust Fluid) reverting valve. The reverting valve (also referred to as the reductant purge control valve or vent valve) is responsible for reversing the flow of DEF back into the tank when the engine is shut down to prevent freezing and crystallizing.

• Tier 4a
• Magnum series (235-340 Series 4)
• Steiger series (350-600)
• Quadtrac / Rowtrac
• Puma series
• Axial-Flow series (7230, 8230, 9230, 7240, 8240, 7250)

1. 1

   Check for related codes (19082, 19083, or 19084) which indicate broader issues with the Voltage Supply 3 (UB3) circuit that powers the reverting valve.

2. 2

   Inspect the wiring harness running between the DCU and the DEF Supply Module (Pump) for chafed wires, rubbed insulation, or pinch points causing a short to ground.

3. 3

   Disconnect the electrical connector at the DEF Supply Module and inspect the pins for water intrusion, corrosion, or adhering foreign material.

4. 4

   Use a multimeter to test the reverting valve supply circuit for continuity to ground. If the harness tests good, the short is internal to the valve itself.

1. 1

   Safely Power Down

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Isolate the Short

   If your multimeter testing in the diagnostic phase revealed a short in the chassis harness, repair the damaged wire or replace the pigtail/harness.

3. 3

   Access the DEF Supply Module

   If the harness is good, the internal reverting valve has failed. Locate the DEF Supply Module (typically mounted near the base of the DEF tank).

4. 4

   Disconnect Lines

   Carefully disconnect the DEF fluid lines (suction, pressure, and backflow) from the module. Have a clean catch pan ready, as residual DEF will spill.

5. 5

   Remove the Module

   Unplug the main electrical connector and unbolt the DEF Supply Module from its mounting bracket.

6. 6

   Install New Module

   Mount the replacement DEF Supply Module. Reconnect the fluid lines securely to prevent air leaks, and plug in the electrical connector.

7. 7

   Prime and Test

   Reconnect the battery. Use the Case IH Electronic Service Tool (EST) to clear the DCU fault codes. Run a DEF system prime/dosing test via the software to ensure the pump builds pressure and the reverting valve operates correctly without throwing the code again.