TPM External Interference 08 4.8

[740iS]

I've read just about everything I can find on this subject and still nothing specific as to cause and resolution. The most common response is that the receiver antenna for the TPM system is bad or one to all four wheel sensors have died.

With that in mind, I am going to replace the antenna first. Then, if needed, look at the wheel sensors when I get new tires next year.

Question is, has anyone come up with a definitive cause for the error? Also, can anyone tell me where this antenna is specifically located on my 08 X5?