Fendt A.1.39 – ECU, enhanced control, electric auxiliary control valves: Spool valve fault, valve 3 (Y017)

The main piston of the auxiliary control valve 3 (Y017) cannot return to its neutral position when switched on, or the valve actuator is not in the neutral position. The valve remains set. This is explicitly flagged as being caused by oil contamination physically preventing the spool valve's main piston from returning to neutral.

• 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
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• Fendt 300 Vario series
• Fendt Farmer 400 / 400 Vario series (e.g., 409, 410, 411, 412)
• Fendt Favorit 700 / 700 Vario series (e.g., 711, 712, 714, 716)
• Fendt 800 Vario series (e.g., 815, 817, 818)
• Fendt Favorit 900 / 900 Vario series (e.g., 916, 920, 924, 926, 930, 939)

1. 1

   Check the hydraulic/transmission oil condition. Look for dark oil, burnt smells, or visible metal/debris contamination on a clean white cloth

2. 2

   Inspect the transmission/hydraulic oil filter and suction strainer for blockages that could force the bypass valve to open and circulate contaminated oil

3. 3

   Inspect the wiring harness and connector at the Y017 valve (Valve 3, typically red) for corrosion or loose connections, which can mimic mechanical binding faults

4. 4

   Check the control pressure (M5) and inspect the diaphragm accumulator to ensure the valve is receiving the correct pilot pressure to actuate and return

1. 1

   Relieve Pressure

   Ensure the tractor is off, implements are lowered, and all hydraulic pressure is relieved from the system.

2. 2

   Access the Valve Block

   Locate the auxiliary control valves on top of the rear axle housing or underside of the central control block. Remove the right step, right auxiliary tank, or rear metal panels to access it.

3. 3

   Remove Valve Y017

   Disconnect the electrical connector (X328) from Valve 3 (Y017 - Red). Unbolt and remove the spool valve from the manifold block.

4. 4

   Clean and Inspect

   Disassemble the spool valve and clean the main piston and bore with hydraulic solvent. Look for scoring or deep scratches caused by debris. If the piston is scored, the valve must be replaced.

5. 5

   System Flush

   If heavy contamination is found, drain the hydraulic/transmission oil, replace the main hydraulic filters, clean the suction strainer, and flush the system to prevent the new valve from suffering the same fate.

6. 6

   Install New Valve

   Mount the new or cleaned valve, torque to OEM specifications, and reconnect the X328 electrical connector.

7. 7

   EOL Programming

   Perform EOL reprogramming/calibration via the FENDIAS diagnostic tool to teach the ECU the new valve's neutral position.