Special Notes For Tire 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 tires 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 tire, read out the remaining life span of the wheel electronics unit (battery capacity) using the PIWIS Tester. 
• For vehicles with Tire 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

1. self-locking (Torx) screw - replace 
2. Wheel electronics
3. Valve, complete (No. 5 to No. 7)
4. Valve cap
5. Valve body with valve insert
6. Double chamfered washer
7. Union nut
8. Wheel electronics assembled

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

   • The wheel electronics unit is removed
   • The self-locking 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
   • Tire sealing compound (tire sealing liquid) has been used
   • The service life of the battery is exceeded
   • There is a fault inside the wheel electronics unit.