how to fix my BMW 3 Series E90/E91 (2005-2012) fuel gauge not working properly

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Tools Required: OBD-II scanner, multimeter, socket set, and screwdrivers.

2. Access the Fuel Sender Unit

• Remove the rear seat or trunk panel to access the fuel pump assembly.
• Disconnect the fuel pump electrical connector and any fuel lines attached.
• Unscrew the retaining ring and carefully lift the fuel pump assembly out of the tank.

3. Inspect the Fuel Sender Unit

• Visually inspect the fuel sender unit for signs of damage or wear.
• Use a multimeter to measure the resistance across the sender's terminals while moving the float arm; the resistance should change smoothly.

4. Replace the Fuel Sender Unit (if necessary)

• If the sender is faulty, remove it from the assembly and replace it with a new unit.
• Reinstall the new fuel sender unit, ensuring it is secured properly and the float moves freely.

5. Reassemble the Fuel Pump Assembly

• Carefully place the fuel pump assembly back into the tank, ensuring all components are aligned correctly.
• Reattach the retaining ring and reconnect the fuel lines and electrical connectors.

6. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the vehicle and check if the fuel gauge is functioning accurately and consistently.