Fendt A.1.44 – Enhanced Control ECU: Spool valve fault, valve 4. Main piston travel too short due to drop of control pressure below 22 bar

The valve automatically moves into the neutral position as a safety measure. This is most frequently caused by the hydraulic oil temperature being too low, which prevents the valve actuator from reaching its commanded position due to thick, cold fluid. It can also be caused by a genuine drop in pilot/control pressure.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
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• 818 Vario COM III
• 820 Vario COM III
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• Fendt Favorit 700 Vario
• Fendt Favorit 900 Vario
• Fendt 300 Vario Series
• Fendt 800 Vario Series
• Fendt 900 Vario Series

1. 1

   Check hydraulic fluid temperature to ensure the oil is not too cold and thick

2. 2

   Test control pressure at test port M5 using a pressure gauge (must not drop below 22 bar)

3. 3

   Inspect the diaphragm accumulator to ensure it is holding the correct pre-charge and maintaining system pressure

4. 4

   Check the RV7/FP (pilot pressure/relief) valve to ensure it is not sticking or bypassing fluid

1. 1

   Warm-Up & Reset

   Start the tractor and allow the hydraulic system to reach operating temperature. Cycle the ignition to reset the Enhanced Control ECU. Test Valve 4 (Y018) via the joystick or fender controls.

2. 2

   Pressure Testing

   If the valve still defaults to neutral and throws A.1.44, connect a hydraulic pressure gauge to test port M5. Actuate the valve. If the pressure drops below 22 bar, the issue is supply-related, not the valve itself.

3. 3

   Accumulator Replacement

   If the pressure drops rapidly during actuation, depressurize the hydraulic system and replace the diaphragm accumulator, as it has likely lost its nitrogen charge.

4. 4

   Valve Replacement

   If the control pressure at M5 is steady above 22 bar but the valve actuator still falls short, replace the Y018 spool valve slice. Clean the area, relieve all hydraulic pressure, disconnect the electronic CAN/power connector (X329), unbolt the tie rods, remove the faulty Valve 4 slice and replace it with a new unit using new O-rings. Re-torque the tie rods and program/calibrate the new valve for position 4 in the Fendt EOL program using FENDIAS.