Deutz-Fahr M70 – Engine ECU (EMR / MVCU): EGR valve: voltage too low on the power circuit / Short circuit to ground

The engine control system has detected that the electrical circuit powering the Exhaust Gas Recirculation (EGR) valve has shorted to ground, resulting in insufficient voltage to operate the valve. This condition typically forces the machine into a derate mode, causing a reduction in engine torque and speed.

• Series 4E (4070E, 4080E, 4090E, 4100E)
• Series 5D / 5D VSF TTV (5080D, 5090D, 5090DF, 5100DF)
• Series 5G (5080G, 5090G, 5100G, 5120G)
• Series 6 Agrotron (6120, 6130, 6140)

1. 1

   Check battery voltage to ensure the system is receiving adequate base voltage, as low voltage can trigger power circuit faults.

2. 2

   Inspect the wiring harness between the Engine ECU and the EGR valve for a short circuit to ground. Specifically, test the continuity and resistance at ECU pins A36, A04, and A19.

1. 1

   Disconnect Battery

   Always disconnect the battery before servicing ECU-linked emissions components.

2. 2

   Test and Repair Wiring

   If the multimeter test reveals a short to ground in the harness (e.g., rubbed through wire insulation touching the engine block), repair the damaged section of the harness.

3. 3

   Replace the EGR Valve

   If the battery voltage is correct and the wiring harness tests perfectly fine, the internal circuitry of the EGR valve itself has failed and shorted out. Remove the defective EGR valve and install the replacement.

4. 4

   Clear Error Memory

   Reconnect the battery, turn the ignition key Off/On, and use a diagnostic tool (like SerDia or an equivalent scanner) to clear the error memory.

5. 5

   Verify Repair

   Run the engine and verify that the torque/speed reduction derate has been lifted and the code does not return.