Fendt 1.2.34 – Engine Control Unit (ECU) / EDC / EMR: S034 - Switch, coolant level

Coolant outside of setpoint level (Coolant level too low). The system warns of Major engine damage if ignored. The fault code can only be cleared temporarily and will repeat every 2 minutes until the underlying issue is resolved.

• 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) / Farmer 400
• Fendt 700 Vario (COM III) / Favorit 700
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III) / Favorit 900
• Fendt 9000 Series
• Favorit 916
• Favorit 920
• Favorit 924
• Favorit 926
• Fendt Vario 822
• Fendt Vario 824
• Fendt Vario 927
• Fendt Vario 930
• Fendt Vario 933
• Fendt Vario 936
• Fendt Vario 939

1. 1

   Check the physical coolant level in the expansion tank. If it is low, the sensor is doing its job.

2. 2

   If the coolant level is fine, consult the wiring diagram (Sheet 35 or Sheet 24) for the EDC control/Dashpanel circuit. Look for a broken wire or short circuit.

3. 3

   Check if a secondary code, 5.1.9F, is present. This indicates a signal fault with the S034 switch (sensor failure or hard electrical fault).

4. 4

   Connect the SERDIA / Fendias diagnostic tool to read out the KWP code (FC:0025) and monitor the live state of the S034 switch.

1. 1

   Safety First

   Park the tractor on level ground, turn off the engine, and allow the cooling system to depressurize and cool down completely to prevent severe burns.

2. 2

   Top Up Coolant

   If the diagnostic check revealed low coolant, top up the expansion tank to the specified setpoint using the OEM-approved coolant mixture. Run the engine and check if the code clears.

3. 3

   Inspect the Sensor

   If the tank is full but the code persists, locate the S034 coolant level switch on the expansion tank. Disconnect the 2-pin electrical connector and inspect for corrosion or water ingress.

4. 4

   Replace the Sensor

   Drain a small amount of coolant from the system so the level drops below the sensor port (or use a vacuum tool to hold the coolant in place). Unthread/unclip the faulty S034 switch from the expansion tank. Install the new sensor and reconnect the wiring harness.

5. 5

   Refill and Clear

   Top the coolant back up to the correct level. Connect the SERDIA diagnostic tool and clear the error code (FC:0025).