General Information On Wheel Electronics

The Tyre Pressure Monitoring (TPM) system is designed to constantly monitor the tyre pressure when the vehicle is moving and stationary. One set of electronics -8-  per tyre is mounted in the rim well base. These measure tyre pressure and temperature at regular intervals and transfer the values to a central control unit via a high-frequency route. The control unit evaluates the information and transfers the data to the instrument cluster if required. In this way, the driver is warned and informed if the tyre pressure needs to be adjusted.

There are two different types of wheel electronics -8-  . Wheel electronics units with amplified transmitting power are used on the Cayenne. These transmit in the high-frequency range of:

• 433 MHz or 315 MHz.

The following points can be used as distinguishing features: 

• The labelling - 433 MHz or 315 MHz.
• and/or the colour (dark grey - 433 MHz; light grey - 315 MHz).
• The part number.
• No stars on the left and right of the elongated slot.

Valve complete with screw -1, 3 and 4- has to be replaced if: 

• The wheel electronics unit is removed.
• The self-locking Torx screw -1-  is loose.
• The valve body -5-  is bent.
• The union nut -7-  is loose.

The wheel electronics unit -2- must be replaced if: 

• The housing is visibly deformed.
• The filter surface (round, porous section on the back of the wheel electronics) is so badly soiled that it can no longer be cleaned by wiping.
• Tyre sealant (tyre sealing liquid) has been used.
• The battery has exceeded its service life.
• There is a fault inside the wheel electronics unit.

Fig 1: 3rd Generation Wheel Electronics Components Location

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Wheel electronics 3rd generation