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I have an Audi Tyre Pressure Monitoring System (TPMS) module from the USA, which therefore means it operates on 315 MHz. It was not available in Europe and hence there isn't a 433 MHz version available.

However, interestingly there is a very similar Hyundai module that operates at 433 MHz. I don't have one at hand and I also doubt it would be compatible with my car due to CANBUS protocols etc.

What I am wondering, and might be completely wrong, is if it is possible to change the frequency by swapping the antenna?

See attached the Audi 315 MHz module and Hyundai 433 MHz module. The angles are different but you can see that the Hyundai antenna is slightly shorter by 30 mm or so.

Audi 315MHz

Hyundai 433MHz

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  • \$\begingroup\$ scan the data matrix label on the silver component ... it may reveal a clue \$\endgroup\$
    – jsotola
    Jan 20 at 18:12
  • \$\begingroup\$ I did wonder what that component was. I will give that a try \$\endgroup\$ Jan 21 at 13:36

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No, the antenna is just the means to get from wired to wireless. Different frequencies calls for different antenna designs but it does not set the frequency in this case. The frequency is mainly controlled by one of the ICs on the board (ignoring tuning networks, amplifiers and similar).

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    \$\begingroup\$ Probably more than just one IC. But your point in well taken. The antenna is the smallest part of this problem. \$\endgroup\$
    – SteveSh
    Jan 20 at 13:50
  • \$\begingroup\$ Thanks, I was hoping it wasn't something like that. Other Audi modules allow the frequency to be set via diagnostics software, but I guess it was omitted in this one as it wasn't ever intended for Europe. \$\endgroup\$ Jan 21 at 13:37
  • \$\begingroup\$ @MarkTickner That’s still a possibility, but just changing the antenna won’t do it. From their perspective, it would be a matter of inventory management versus cost to have one generic programmable one versus two different designs. \$\endgroup\$
    – winny
    Jan 21 at 14:22

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