Fendt 04.1.B7 – A050 - ECU, basic control unit: Incorrect checksum for B009 Discharge temperature sensor

The control unit has detected an invalid checksum in the EEPROM/memory block associated with the B009 discharge temperature sensor's calibration or parameters.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario (e.g., COM III)
• Fendt 400 Vario (e.g., 409, 410, 411, 412)
• Fendt 700 Vario (e.g., 711, 712, 714, 716)
• Fendt 800 Vario (e.g., 815, 817, 818, 820)
• Fendt 900 Vario (e.g., 916, 920, 924, 926, 930, 936 COM III and S4 generations)

1. 1

   Verify B009 sensor integrity to ensure it is not shorted or sending erratic signals that could corrupt parameter readings.

2. 2

   Measure B009 sensor resistance across the pins (often routed through connector X158). Expected values: ~210 ohms at 50°C, ~147 ohms at 60°C, ~51 ohms at 87°C, ~37 ohms at 100°C, ~24 ohms at 110°C.

3. 3

   Inspect the wiring harness between the B009 sensor and the A050 ECU, specifically checking the signal line and Earth pin for chafing, corrosion, or poor pin fitment.

1. 1

   Connect diagnostic interface

   Connect the FENDIAS diagnostic interface to the tractor's diagnostic port.

2. 2

   Establish communication

   Turn the ignition ON and establish communication with the A050 - ECU, basic control unit.

3. 3

   Perform EOL programming

   Navigate to the programming/calibration menu and perform EOL (End of Line) programming for the A050 ECU. This will rewrite the correct parameters and clear the corrupted checksum data.

4. 4

   Replace ECU

   If the EOL programming fails to take, or if the fault immediately returns, the A050 ECU may have an internal EEPROM failure requiring ECU replacement.

5. 5

   Replace sensor and reprogram

   If the diagnostic checks revealed a faulty B009 sensor (e.g., open circuit or out-of-spec resistance), replace the sensor, clear the fault codes, and then perform the EOL programming.