Fendt 09.1.40 – Hydraulics / Power Lift Control Unit (A005 ECU or A050 Basic Control Unit): S021 - Switch (external), raise front power lift

This fault code indicates a signal fault or 'key fault' originating from the external push button used to raise the front power lift. The system logs this code when it detects a faulty button, a stuck button, or a 'double actuation' (e.g., the system receives simultaneous signals to raise and lower). The external front power lift button is rendered inoperable by the system for safety until the next trouble-free cold start.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt Farmer 300 and 400 series
• Fendt Favorit 500, 700, and 900 series
• Fendt Vario 300, 400, 700, 800, and 900 series (including COM III and S4 generations)

1. 1

   Visually inspect the S021 external raise button on the front linkage for physical damage, heavy dirt/debris ingress, or physical sticking.

2. 2

   Check the adjacent 'Lower' button (S022) to ensure it is not also stuck, which causes a double actuation fault.

3. 3

   Disconnect the switch and inspect the wiring harness and connector pins for corrosion, moisture ingress, or short circuits to ground.

4. 4

   Perform a continuity test on the S021 switch using a multimeter; it should only have continuity when physically pressed.

5. 5

   Perform a complete power cycle ('trouble-free cold start') to see if the code clears after cleaning or un-sticking the button.

1. 1

   Power Down

   Turn off the tractor, remove the key, and ideally disconnect the battery ground to prevent accidental short circuits.

2. 2

   Access the Switch

   Locate the external front power lift control panel on the front linkage housing.

3. 3

   Disconnect Harness

   Carefully unplug the weather-sealed electrical connector from the back of the S021 switch.

4. 4

   Remove the Switch

   Depress the retaining clips or remove the locking nut holding the switch into the mounting bracket/panel, and push the switch out.

5. 5

   Install New Switch

   Insert the replacement switch into the panel until it clicks or is securely fastened.

6. 6

   Reconnect

   Plug the electrical harness back in. Ensure the weather seal is intact to prevent future moisture ingress.

7. 7

   Clear Fault

   Reconnect the battery and perform a cold start of the tractor. The system should run its self-check and clear the 09.1.40 code.

8. 8

   Test Operation

   Test both the external raise (S021) and lower (S022) buttons to confirm the front power lift operates smoothly without throwing new codes.