Deutz-Fahr I20 – Instrument Panel: Fuel level sensor is short-circuiting to battery positive

The control module is detecting battery voltage on the sensor's signal circuit, which typically points to a wiring harness short (a power wire rubbing against the sensor signal wire) or an internal failure within the fuel sender unit itself.

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Deutz-Fahr Agrofarm 85 and 100
• Deutz-Fahr Agrocompact (f60, f70, f80, f90)
• Same Explorer 90

1. 1

   Disconnect the fuel level sensor and measure the resistance output between the sensor's signal pin and machine ground. An open or shorted reading indicates a faulty sensor.

2. 2

   Disconnect both the instrument panel ECU and the fuel level sensor. Turn the ignition on and measure the voltage on the sensor signal wire in the harness. If battery voltage (12V) is present, the wiring harness has a short to power.

3. 3

   If the sensor tests good and the harness shows no shorts, check the instrument panel ECU for an internal fault.

1. 1

   Disconnect Power

   Disconnect the negative terminal of the battery to prevent electrical spikes.

2. 2

   Access the Sender

   Locate the fuel level sensor/sender unit on the top or side of the fuel tank.

3. 3

   Harness Repair

   If your diagnostics revealed a short to battery in the harness, trace the signal wire back to the instrument panel. Look for pinched wires, melted insulation, or chafing against the frame. Repair the damaged section with solder and heat shrink, or replace the harness section.

4. 4

   Sensor Replacement

   Disconnect the electrical connector from the fuel sender unit. Clean the area around the sensor to prevent debris from falling into the fuel tank. Remove the retaining ring or mounting bolts holding the sensor in place. Carefully extract the old floating fuel level sensor from the tank. Insert the new sensor, ensuring the new rubber gasket/O-ring is properly seated to prevent fuel leaks. Tighten the mounting bolts/ring and plug in the electrical connector.

5. 5

   Reassembly and Testing

   Reconnect the battery. Turn the ignition key to the ON position. Verify that the fuel gauge registers the correct fuel level and that the I20 fault code has cleared from the instrument panel display.