Fendt 5.1.9E – Dashpanel / Instrument Cluster (A007): Engine coolant level switch - Coolant level too low or empty

Coolant level too low or empty. This is a critical priority fault indicating a severe risk of major engine damage. The system only allows the operator to temporarily acknowledge or clear the warning; the error message will aggressively repeat every 2 minutes (120 seconds) until the coolant level is restored.

• 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
• 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 Farmer 400 Vario series
• Fendt Favorit 700 and 900 series
• Fendt 300, 400, 700, 800, and 900 Vario series (including COM III and S4 generations)
• 409-415
• 711-718
• 818-820
• 916-930

1. 1

   Physically verify the coolant level in the expansion tank before assuming the sensor is bad

2. 2

   If the tank is low or empty, inspect the radiator, hoses, water pump, and engine block for active coolant leaks

3. 3

   If the coolant level is full, inspect the S034 switch's electrical connector (X244) for corrosion, moisture ingress, or broken wires

4. 4

   Check if the float inside the expansion tank switch is stuck due to scale or debris, which can falsely trigger the alarm

1. 1

   Safety First

   Ensure the tractor is parked on level ground, the engine is turned off, and the cooling system has completely cooled down. Never open the cooling system when hot and pressurized.

2. 2

   Locate the Sensor

   Open the bonnet. The S034 coolant level switch is located at the top of the engine, mounted directly into the coolant expansion reservoir.

3. 3

   Top-Up (If Applicable)

   If the fluid is simply low, top off the expansion tank to the specified setpoint with OEM-approved coolant. Turn the ignition ON to verify the code clears.

4. 4

   Sensor Removal

   If the sensor has failed mechanically (stuck float) and needs replacement, disconnect the X244 electrical connector from the switch.

5. 5

   Remove Switch

   Carefully unthread or unclip the S034 switch from the expansion tank. Because it is located at the top of the reservoir, coolant loss should be minimal, but have a shop rag ready.

6. 6

   Installation

   Install the new coolant level switch. If it is a threaded plastic fitting, be careful not to overtighten it.

7. 7

   Reconnect Harness

   Reconnect the X244 electrical harness.

8. 8

   Final Verification

   Top up any displaced coolant, start the tractor, and monitor the dashpanel to ensure fault code 5.1.9E does not return.