0A.20.28

Massey Ferguson 0A.20.28 – Dash / Mid Mount Valve Module: External Hydraulic Valve 2 Issue

Issue description

Malfunction or fault detected within the circuit or mechanical operation of the second external hydraulic spool valve.

Use a compatible Massey Ferguson diagnostic tool or interface device to confirm code 0A.20.28 is active.
Check the wiring harness and connectors leading to External Hydraulic Valve 2 for corrosion, loose pins, or damaged wires.
Monitor the Spool Position Sensor value via the diagnostic tool to see if it is reading out of range or stuck.
Verify that there is proper communication between the Dash display and the Valve Module.

Power down and relieve pressure
Power down the tractor and relieve all hydraulic system pressure.
Locate valve
Locate External Hydraulic Valve 2 at the rear remote stack (or mid-mount block, depending on tractor configuration).
Clean electrical contacts
Disconnect the electrical connector to the valve's solenoid and spool position sensor. Clean the contacts with electrical contact cleaner and apply dielectric grease.
Replace faulty component
If the wiring is intact but the code persists, the spool position sensor or the electronic solenoid head on Valve 2 is likely faulty and needs to be replaced.
Clear DTCs
After replacing the faulty component, reconnect the harness, power on the tractor, and use a diagnostic tool to clear the DTCs.
Test operation
Test the hydraulic remote operation to ensure the fault does not return.

(3)

External Hydraulic Valve 2 Assembly (Spool Valve)
Parts will vary heavily depending on whether the tractor is a 4700, 5600, 7600, or 7700 series.

Spool Position Sensor
Often sold separately or as part of the electronic valve head.

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