Fendt 5.1.98 – Enhanced Control ECU (A002 / E-Box): LS (Load Sensing) pump pressure-operated switch — Minimum pressure is not reached

The system detects that the LS hydraulic pump pressure has fallen below the minimum threshold (typically 8 bar). The fault code is only triggered if the condition persists for at least 1 second while the engine is running at over 1000 RPM.

• 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 / 400 Vario (COM III)
• Fendt Favorit 700 / 700 Vario (COM III)
• Fendt Favorit 900 / 900 Vario (including 916, 920, 924, 926, 930, 933, 936, 939)
• Fendt 300 Vario (COM III)
• Fendt 800 Vario (COM III)

1. 1

   Verify the issue occurs when the engine is running above 1000 RPM, as the ECU ignores low-pressure readings at idle

2. 2

   Check hydraulic fluid levels and inspect hydraulic filters for clogs that could starve the LS pump

3. 3

   Perform electrical tests at the S025 switch connector (X235) for the correct test sequence voltage (0 / 2.4 V)

4. 4

   Inspect the wiring between the S025 switch and the E-box for a short-circuit to earth (0 / 0 V) or a wire break (0 / 8 V)

5. 5

   Perform a mechanical pressure test by plumbing a gauge into the LS pump test port to verify if the pump is failing to produce 8 bar or if the switch is sending a false reading

1. 1

   Preparation

   Park the tractor on a level surface, lower all hydraulic implements, turn off the engine, and relieve all hydraulic pressure.

2. 2

   Access the Component

   Locate the S025 LS pump pressure-operated switch. It is typically threaded into the LS pump housing or the central control block. Depending on the model, you may need to remove access panels, the battery box, or partially drain the fuel tank to reach the pump area.

3. 3

   Replace the Switch

   If diagnostics point to a faulty switch: Disconnect the X235 electrical connector from the S025 switch. Unscrew the pressure switch from the hydraulic port (have a rag ready to catch residual oil). Install the new pressure switch with the appropriate O-ring/sealant and tighten to OEM torque specs. Reconnect the wiring harness.

4. 4

   Replace the LS Pump

   If mechanical pressure is confirmed low: Drain the hydraulic fluid from the system. Disconnect all hydraulic hoses and lines from the LS pump, capping them to prevent contamination. Remove the mounting bolts and brackets securing the pump to the drive gear/PTO housing. Remove the pump and install the replacement unit. Reattach all hoses, refill the hydraulic system with fresh, approved fluid, and bleed the system.

5. 5

   Finalization

   Start the tractor, run it above 1000 RPM, and test the hydraulic functions. Clear the fault codes from the E-Box using a diagnostic tool or the terminal reset procedure.