1. Locate the airbag control module. In the 540i, it's located under the front seat.
2. Remove the cover of the airbag control module. There are two screws that hold the cover in place.
3. Locate the reset button on the airbag control module. It's usually a small, black button.
4. Press and hold the reset button for 10 seconds.
5. Release the reset button.
6. Replace the cover of the airbag control module.
7. Start the engine of your BMW 540i. The airbag light should be off.
If the airbag light does not turn off, you may need to take your car to a BMW dealer to have the airbag system checked.
