See the "Important safety notes" section.

If ESP® detects that the vehicle is deviating from the direction desired by the driver, one or more wheels are braked to stabilize the vehicle. If necessary, the engine output is also modified to keep the vehicle on the desired course within physical limits. ESP® assists the driver when pulling away on wet or slippery roads. ESP® can also stabilize the vehicle during braking.

If ESP® intervenes, the ESP® warning lamp flashes in the instrument cluster.

WARNING
Under no circumstances should you deactivate ESP® when the ESP® warning lamp in the instrument cluster flashes. Proceed as follows:

Failure to observe these guidelines could cause the vehicle to skid. ESP® cannot prevent accidents resulting from excessive speed.

Only operate the vehicle for a maximum of ten seconds on a brake test dynamometer. Switch off the ignition.
Application of the brakes by ESP® may otherwise destroy the brake system.

Function or performance tests may only be performed on a 2-axle dynamometer. If you wish to operate the vehicle on such a dynamometer, please consult an authorized Mercedes-Benz Center beforehand. You could otherwise damage the drive train or the brake system.

Only use wheels with the recommended tire sizes. Only then will ESP® function properly.