New Holland P20A3 – DCU: Reductant Purge Valve Short Circuit High

The Engine Control Module (ECM) or Dosing Control Unit (DCU) has detected an abnormally high voltage or resistance in the electrical circuit of the reductant purge control valve. This valve is part of the Selective Catalytic Reduction (SCR) system and manages the flow of Diesel Exhaust Fluid (DEF), clearing the lines after engine shutdown. A 'Circuit High' condition typically indicates an electrical issue such as a short circuit to a power source, a faulty valve, damaged wiring, or a poor ground connection.

• T7.170
• T7.185
• T7.230
• T7.245
• T8.320
• T8.380
• T8.410
• T8.435
• CR6.80
• CR8.90
• Magnum 220
• Magnum 250
• Magnum 280
• Magnum 340
• Magnum 380

1. 1

   Inspect the wiring harness connected to the reductant purge control valve for chafing, melting, or breaks

2. 2

   Check connectors for corrosion, moisture intrusion, or loose pins

3. 3

   Trace the wiring to check for a short to power (signal wire contacting a power source)

4. 4

   Test the reductant purge control valve's internal resistance with a multimeter or command it via a diagnostic tool

5. 5

   Check Diesel Exhaust Fluid (DEF) quality and level to rule out blockages from crystallized fluid

6. 6

   Review official technical service bulletins for known issues or software calibration updates

1. 1

   Isolate the fault

   Use diagnostic checks to confirm whether the fault lies with the wiring, the connector, or the valve itself.

2. 2

   Repair wiring

   If a wiring issue or short to power is found, repair or replace the damaged section of the harness. Ensure all connections are secure and protected from heat and abrasion.

3. 3

   Clean or replace connectors

   If connectors are corroded or damaged, clean them thoroughly or replace them if the damage is severe.

4. 4

   Replace the valve

   If the reductant purge control valve itself is determined to be faulty after testing, replace the component.

5. 5

   Clear fault codes

   Use a diagnostic tool to clear the P20A3 fault code from the Dosing Control Unit (DCU).

6. 6

   Verify repair

   Operate the machine and run any necessary SCR system verification tests with a diagnostic tool to ensure the fault does not return.