Fendt 1.2.B5 – A020 - Pump control unit: A020 - Pump control unit (injection pump) (EDC) — Fault during pump control unit self-diagnostic test (EEPROM checksum)

The internal memory (EEPROM) of the injection pump's control unit has failed its checksum verification during the system's automated self-diagnostic test. This points to a software corruption, memory loss, or internal hardware failure within the pump's control module, causing the engine to go into a restricted operating mode with reduced engine speed and power.

• 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 Favorit 900 series (chassis number 23/3001 and up)
• Fendt 900 Vario series (916 Vario, 920 Vario, 924 Vario, 926 Vario, 930 Vario)
• Fendt Farmer 400 series
• Fendt Favorit 700 / 700 Vario series
• Fendt 800 Vario series

1. 1

   Check for other fault codes using the FENDIAS diagnostic tool. Address CAN communication timeouts (like 1.2.B4) or power supply faults first, as voltage drops or CAN interruptions can cause false EEPROM errors.

2. 2

   Record the failure and ambient parameters with FENDIAS, delete the fault code memory, and run the tractor to see if the 1.2.B5 code returns.

3. 3

   Inspect the wiring harness and adapter connectors between the A021 EDC Control Module and the A020 Pump Control Module for continuity, short circuits, or discontinuity.

4. 4

   Verify the fuel supply system by checking the primary pressure and the interior pressure of the pump. Ensure there is no air in the fuel system or clogged filters, as severe mechanical fuel issues can trigger erratic pump module behavior.

1. 1

   Save data and clear codes

   Connect the FENDIAS tool and ensure all diagnostic data is saved, then clear the codes.

2. 2

   Prepare for pump removal

   Because the A020 Pump Control Unit is integrated into the electronic injection pump, the standard repair requires removing the entire injection pump assembly.

3. 3

   Disconnect components

   Disconnect the battery and remove the fuel lines and electrical connectors from the injection pump.

4. 4

   Dismount injection pump

   Dismount the injection pump following the mechanical timing procedures outlined in Chapter 2000 (Engine) / Chapter 2712 (Injection) of the workshop manual.

5. 5

   Replace or repair pump

   The pump must either be replaced entirely or sent to an authorized diesel specialist (e.g., Bosch Diesel Service) to have the A020 control unit repaired, reprogrammed, and calibrated on a test bench.

6. 6

   Reinstall and bleed system

   Reinstall the injection pump, bleed the low-pressure and high-pressure fuel systems.

7. 7

   Perform final programming

   Use FENDIAS to clear any residual codes and perform any required end-of-line (EOL) programming or pump synchronization.