The 2003 Mercedes-Benz C240 comes standard with a factory-installed car alarm. When it is activated, the alarm will deter thieves from stealing your vehicle by sounding the horn and flashing the lights for two and a half minutes. You can disable the C240's alarm by using the car remote key that comes with the Mercedes, or by removing the fuse under the hood. This is an easy process that takes a few minutes to do.
Turn off the engine.
Open the bonnet and locate the C240's fuse block found behind the battery.
Remove the fuse block's cover. Remove the fuse puller from the underside of the cover.
Use the fuse puller to remove the fuse marked with the number "8" in the fuse block.
Replace the fuse puller on the underside of the fuse block cover. Place the fuse block cover back on the fuse block. Close the bonnet.
Enable the C240's alarm again by putting the number "8" fuse back in the fuse block.