Fendt A.1.18 – Enhanced Control ECU (A002): Spool valve fault, valve 1 — Main piston cannot return to neutral position because of oil contamination

The main piston inside the auxiliary control valve 1 (Y015) is physically binding or stuck due to debris or contamination in the hydraulic oil, preventing the slider from automatically springing back to its neutral position. The system will typically force the valve into a neutral position or lock it out to prevent undefined and uncontrolled functions.

• 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
• Farmer 409 Vario
• Farmer 410 Vario
• Farmer 411 Vario
• Farmer 412 Vario
• Farmer 413 Vario
• Farmer 414 Vario
• Farmer 415 Vario
• Favorit 711 Vario
• Favorit 712 Vario
• Favorit 714 Vario
• Favorit 716 Vario
• Favorit 718 Vario
• Favorit 916 Vario
• Favorit 920 Vario
• Favorit 924 Vario
• Favorit 926 Vario
• Favorit 930 Vario
• Fendt 815 Vario
• Fendt 817 Vario
• Fendt 818 Vario
• Fendt 820 Vario

1. 1

   Perform a manual actuation test on Valve 1 (Y015, Yellow) to ensure there is no play and the slider returns to the middle position by itself when released

2. 2

   Pull a sample of the hydraulic oil to check for visible metal shavings, sludge, or severe degradation confirming contamination

3. 3

   Verify control pressure is not dropping below 22 bar at the M5 test port and inspect the diaphragm accumulator

1. 1

   Depressurize the System

   Turn off the engine and relieve all hydraulic pressure from the system. Warning: Accumulators and suspension lines can hold up to 200 bar of pressure even with the engine off.

2. 2

   Isolate Valve 1 (Y015)

   Locate the Y015 Auxiliary Control Valve (Position 1, Yellow) on the central control block.

3. 3

   Remove and Inspect

   Remove the spool valve. Inspect the main piston and the bore for scoring, galling, or trapped debris.

4. 4

   Clean or Replace

   If the contamination is minor, the valve can be thoroughly disassembled, cleaned, and flushed. If the piston is scored or permanently binding, the entire Y015 valve assembly must be replaced.

5. 5

   Address the Contamination

   Drain the hydraulic fluid, flush the system, and replace the hydraulic filters (pressure and return). Refill with clean, OEM-approved fluid (e.g., STOU SAE 5W-30, 10W-40, or Fendt Extra Hyd 68).

6. 6

   Reassembly and Calibration

   Reinstall the valve. Connect the FENDIAS diagnostic tool to clear the A.1.18 fault code. If a new valve was installed, an EOL (End of Line) programming/calibration procedure must be performed so the ECU recognizes the new valve on the CAN bus.