Fendt 9.1.58 – A002 - ECU, enhanced control: Y019 - Spool valve fault / Auxiliary control valve — Main piston cannot return to neutral position due to oil contamination.

The main piston (valve slide) inside the auxiliary control valve is physically jamming and failing to return to its neutral/center position due to oil contamination. This can lead to undefined and uncontrolled hydraulic functions. The system typically forces the valve into a neutral position electronically, but mechanical binding prevents it.

• 409 Vario
• 410 Vario
• 411 Vario
• 412 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 715 Vario
• 716 Vario
• 717 Vario
• 718 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario
• Fendt Farmer 400 series
• Fendt Favorit 700 and 900 series
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III)
• Fendt 700 / 700 Vario (COM III)
• Fendt 800 / 800 Vario (COM III)
• Fendt 900 / 900 Vario (COM III)

1. 1

   Manual Actuation Test: Check the manual actuator on the Y019 valve. Manual actuation must not have any play, actuator must move to the centre position by itself.

2. 2

   Hydraulic Oil Inspection: Check the hydraulic oil for heavy contamination, metal shavings, or degraded fluid, which is the primary cause of this code.

3. 3

   Control Pressure Check: Verify the control pressure at measuring point M5. Ensure pressure does not drop below 22 bar.

4. 4

   Accumulator Check: Inspect the diaphragm accumulator and RV7/FP valves to ensure proper pilot pressure is reaching the valve block.

1. 1

   Relieve Pressure

   Turn off the engine and relieve all hydraulic pressure in the system. Warning: Residual pressure up to 200 bar may remain in the accumulators and suspension cylinders even with the engine off.

2. 2

   Access the Valve

   Locate the Y019 valve (Valve 5). Depending on the model, this is typically located on the right entry behind the hydraulic oil tank (requires removing the metal panel) or at the central control block.

3. 3

   Remove the Valve

   Disconnect the electrical connectors and hydraulic lines to the Y019 Bosch SB 23 LS-EHS valve. Remove the valve from the sandwich block assembly.

4. 4

   Clean and Inspect

   Disassemble the spool valve carefully. Clean the internal oil control valve and main piston. Look for scoring or heavy debris.

5. 5

   Reseal or Replace

   If the spool is scored and permanently jammed, the valve section must be replaced. If it can be cleaned, rebuild it using an OEM Bosch seal kit.

6. 6

   System Flush

   Drain the hydraulic oil, replace the high-pressure and return hydraulic filters, and refill with clean, approved hydraulic fluid (e.g., Fendt Extra Trans 10W-40 or STOU SAE 10W-40) to prevent immediate recurrence.

7. 7

   Reinstall and Calibrate

   Reinstall the valve, bleed the system, and clear the fault codes.