Fendt 1.2.78 – A051 - ECU, engine control unit (EDC 7): Short circuit in cylinder bank 1 injector valves

The engine management system has detected a short circuit in the electrical circuit controlling the fuel injectors on cylinder bank 1. To protect the system from electrical damage, the ECU triggers a "Cylinder switch-off" (injection failure) for that bank, which will result in a severe loss of power, rough running, or an engine stall.

• 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 (COM III)
• FENDT 400 Vario (COM III)
• FENDT 700 Vario (COM III)
• FENDT 800 Vario (COM III)
• FENDT 900 Vario (COM III)

1. 1

   Inspect the wiring harness running from the EDC 7 ECU to the injectors on cylinder bank 1 for chafed wires, melted insulation, or rubbing against the engine block

2. 2

   Disconnect the harness at the injectors and ECU to check for oil ingress, water, corrosion, or bent pins that could bridge connections

3. 3

   Measure the resistance across the pins of each injector on bank 1 using a multimeter to check for an internal solenoid short

4. 4

   If wiring and injectors test fine, test the ECU output to determine if the internal injector driver (power stage) has failed

1. 1

   Disconnect Power

   Turn off the tractor ignition and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Injectors

   Remove the necessary engine cowling/bonnet panels to access the Deutz engine's cylinder head and fuel rail.

3. 3

   Repair/Replace Wiring

   If a short is found in the harness, repair the damaged wires using heat-shrink solder connectors, or replace the injector wiring harness entirely.

4. 4

   Replace Faulty Injector

   If an injector fails the resistance test, remove the high-pressure fuel line, unbolt the injector clamp, and extract the faulty injector. Install a new injector with new copper sealing washers and O-rings. Torque the clamp and fuel lines to OEM specifications.

5. 5

   Clear the Fault Code

   Reconnect the battery. Connect a laptop with the SERDIA (Deutz/Fendt) diagnostic software to the tractor's diagnostic port. The OEM manuals explicitly state that this specific EDC 7 error must be manually deleted using SERDIA (Action: "SERDIA - delete error") after the physical repair is made.

6. 6

   Test Run

   Start the engine and verify that all cylinders are firing smoothly and the code does not return.