The way to Reset the Oil Service Light on a 1997 BMW 540I

    1

    Turn the ignition on but do not crank the engine. If the motor is running, the reset tool is not going to function correctly.
    2

    Open the hood of the 540I and take off the cap covering the diagnostic port. The diagnostic port on the BMW 540I is located below the hood on the passenger's side.
    3

    Place the reset tool onto the diagnostic port and wait for the tool's yellow light to illuminate.
    4

    Press the tool's switch until the Kfz diagnosegeraet red light flashes seven times to reset the oil service light.
    5

    Take the key out of the ignition, remove the tool from the diagnostic port, replace the cap onto the port and drop down the hood of one's BMW.