Mercedes-Benz S 450 4MATIC Operator's Manual page 659

Practical hints
What to do if ...?
Display Possible cause/consequence
Tire Pressure Monitor The Advanced TPMS is deactivated be-
Inoperative cause wheels without proper sensors were
No Wheel Sensors installed.
Tire Pressure Monitor The Advanced TPMS is unable to monitor
Currently Unavailable the tire inflation pressure due to:
a nearby radio interference source
the on-board voltage is too low
excessive wheel sensor temperatures
658
Possible solution
Have the wheel sensors installed by an authorized
Mercedes-Benz Center.
As soon as all wheels with sensors have been mounted, the
Advanced TPMS is switched back on after driving for several
minutes.
As soon as the causes for the malfunction are no longer present,
the Advanced TPMS automatically becomes active again after a
few minutes of driving.