Your remote key fob not working after replacing it or the battery? Here's a possible reason why...

[vbelsky]

The E85 Z4 and E46 3-series convertible have the FZV antenna amplifier (remote locking amplifier) built into the rearview mirror.

Circled in green.

This piece can't be bought on its own. If its faulty, your best bet is a used E46 convertible mirror, replacement mirror of the original, or sending the module to a specialist for repair, such as Scott at bmwgm5.com (no affiliation).

 

[Magicarcher]

Agree with your findings. RF key fobs not working are mostly down to dead batteries, but in my case even after replacing batteries and pairing it didn't work. After weeks of frustration I realised it was pairing OK because I was sitting next to the mirror to do it but as soon as I moved outside the car it stopped working. Decided to test it from outside the car with the RF fob up against the front screen by the mirror and it worked. The issue was the RF receiver in the mirror had gone faulty and it's range had been reduced. Didn't know you could just buy receiver, so bought a SH mirror from ebay. fitted in 15 minutes and keyfob worked again

 

[ph001]

Does a new mirror / pcb needed to be coded to the car or the key in any way?

 

[Silverzedtom]

Hope you don’t mind OP. But I’ll just leave this here in case anyone needs a mirror.

https://z4-forum.com/forum/viewtopic.php?f=7&t=101755&hilit=Mirror

 

[buzyg]

Another little nugget of info, cheers op.

 

[Magicarcher]

Does a new mirror / pcb needed to be coded to the car or the key in any way?

No. I fitted a new interior mirror of a 2007 into my 2005 no need to code (and it made my RF work). BMW changed the interior mirror part number (supplier change I think), the 2007 has the latest part fitted. i read on another forum that the newer models were less prone to fluid leakage.