Special Notes For Tyre Pressure Monitoring (Tpm)

Information 

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Overview of wheel electronics

• If the old wheels are still near the vehicle after assembly work (for example changing winter tyres and/or wheels from another vehicle with TPM), these will still be detected by the system. If one or more of these wheels has a minimum pressure of more than 0.5 bar (7 psi) below the required pressure, this can trigger a warning in the instrument cluster. In this case, remove the wheels or adjust the vehicle outside the radio range of these wheels using the PIWIS Tester. 
• Before changing a tyre, read out the remaining life span of the wheel electronics unit (battery capacity) using the PIWIS Tester. 
• For vehicles with Tyre Pressure Monitoring (TPM), the valve and wheel electronics -arrow- are only replaced in exceptional cases. The following points can make replacement necessary. 

Fig 1: 3rd Generation Wheel Electronics Components Location

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

3rd generation wheel electronics

Valve must be replaced complete with screw -1, 2, 3- if: 

• The wheel electronics unit is removed
• The self-locking fastening 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 back of wheel electronics) is so badly soiled that it can no longer be cleaned by wiping
• Tyre sealing compound (tyre sealing liquid) has been used
• The service life of the battery is exceeded
• There is a fault inside the wheel electronics unit.