Fendt 07.1.A1 – A039 (MFA, Multifunction Armrest) / A050 (Basic Control Unit ECU): A039 - MFA, multifunction armrest. Cab button, FRONT PTO.

This code indicates a communication fault with the front PTO cab button located on the multifunction armrest (MFA). The key/button in the cab will not function, and the front PTO becomes inoperable or disengages.

• 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 200 V/F/P Vario series (207, 208, 209, 210, 211)
• Fendt 300 Vario COM III
• Fendt 400, 700, 800, and 900 Vario COM III / SCR / S4 series

1. 1

   Check the physical condition of the front PTO button on the MFA. Ensure it is not physically stuck, as pressing the button for more than 30 seconds triggers plausibility errors that can shut down the PTO.

2. 2

   Check the wiring harness, plug connections, and CAN bus communication lines between the A039 (MFA) and the A050 (Basic Control Unit).

3. 3

   Verify the fuses supplying power to the MFA and PTO control circuits (e.g., check fuse A013).

1. 1

   Isolate the Fault

   Use a multimeter or diagnostic terminal to verify if the communication loss is isolated to the front PTO button or if the entire A039 MFA is failing to report to the bus.

2. 2

   Replace the Switch/MFA

   If the wiring is intact but the button fails to communicate, replace the faulty front PTO push-button switch on the armrest. If the internal board of the armrest has failed, the A039 MFA module itself may require replacement.

3. 3

   EOL Programming

   If the A039 Multifunction Armrest is replaced, or if the basic control unit requires re-initialization, you must perform EOL (End of Line) programming to restore communication.

4. 4

   Clear the Fault Code

   Canceling a fault message on the screen does not remove it from the system. You must manually confirm, call up, and delete the stored fault code via the terminal. Press the button repeatedly until no more fault codes are indicated.