General Information On Wheel Electronics

The Tyre Pressure Monitoring system is designed to constantly monitor the tire pressure during driving and when the vehicle is stationary. One set of electronics -A-  per tire is mounted in the rim well base. These measure tire 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 combination instrument if required. In this way, the driver is warned and informed if the tire pressure has to be corrected.

Fig 1: Identifying Wheel Electronics

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

There are various types of wheel electronics -A- available. 

The fundamental difference is in the TPM generation (1st generation up to 2008 model or 2nd generation from 2009 model onwards) and also in the frequency (433 MHz or 315 MHz).

1st generation TPM wheel electronics up to 2008 model are not compatible with 2nd generation TPM wheel electronics as of 2009 model  .

If wheels with 1st generation TPM wheel electronics are fitted on a vehicle with 2nd generation TPM wheel electronics (or vice versa), the TPM system will not recognize the wheel electronics. The TPM system is not active and a corresponding warning message appears in the instrument cluster.

In addition, the wheel electronics are reported as defective in the fault memory of the TPM control unit.

The following points can be used as distinguishing characteristics of wheel electronics: 

• Labelling - 433 MHz or 315 MHz
• Refer to the Parts Catalogue (PET) for details of part numbers/current allocation
• Colour
• Without 8 stars (the illustration shows 8 stars, 4 each to the left and right of the slot, wheel electronics with amplified transmission power from the Cayenne)
• Special wheel electronics - 315 MHz: Indicated by 14 slashes

Fig 2: Identifying Wheel Electronics Components

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

1. -A-  - Wheel electronics
2. -B-  - Valve complete (No. 2 to No. 7)
3. -1-  - Self-locking (Torx) fastening screw
4. -2-  - Valve cap (plastic)
5. -3-  - Valve insert
6. -4-  - Union nut
7. -5-  - Washer chamfered on both sides
8. -6-  - Bead seat sealing ring
9. -7-  - Valve