Spare Remote (Key Fob)

[Garec]

I recently bought a 2019 RX 350 for my wife after the car was leased for two years. The car came with only one remote key so I ordered a spare on EBay and had it programmed by a local locksmith.  The remote works except that it must be held close to the Start button - like the procedure for starting the car with a nearly dead remote battery.  I have replaced the battery three times with new batteries, so I don't think that's the problem.  I wanted a spare and this remote works as a spare, but my wife says there is something wrong with it and refuses to use it.  Does anyone know how I can get this remote fully functional without spending a day at the dealer and paying through the nose?  Any suggestions are appreciated.  Thanks

[Les Lex 2018]

I'd call customer Support at Lexus and ask them if a lock smith can even program one of those. My guess is that the programming procedure did not go well or it was not applied using required Lexus procedures.  Lexus dealer can tell you if you have a working FOB. Don't know what they charge for that?

My 2018 key FOB slipped out of my pocket and the RX still started because the wife had her FOB in her purse.  So I didn't realize I had lost it.  Lexus wanted 550 dollars to replace it.

Then I get a call from our friends and they say: Did you know you left your key FOB on our sofa. Close call.  Technology ain't cheap!

 

[Jack Wolff]

If the car starts, programming should be OK. So, the problem is either the battery or the fob antenna. 2025 battery, plus side up. both connections should be checked; the sliver of metal pressing on the bottom can get pressed down & needs to be pried-up(carefully). Otherwise, likely defective antenna.

[Les Lex 2018]

Caution: Just because the VIN got programmed, does not guarantee that the data link was correctly configured.  Placing the key near the start button may be reading a semi-passive chip inside the FOB as a backup to low battery.  Anyone know for sure about that?  There is a YouTube video also that shows you how to replace the battery correctly.  If that does not do the trick, the end result is: Get it pass/fail tested with the proper test equipment. And/or send it back to the seller for replacement. Or give the wife your FOB and you deal with using the Mickey Mouse pass key hidden in the FOB.  Hate it!

[Garec]

Thanks to Les and Jack for trying to help.  The aftermarket fob came with a battery.  I bought a package of two additional batteries and all of them worked as I described and failed to work like my original fob.  I have a battery tester and tested all three batteries and they all test fully charged.  I also removed the battery from the original fob and inserted it into the aftermarket fob and its behavior was unchanged.  I believe it is safe to say the problem is not the battery.  I have also observed that the original fob works flawlessly and the aftermarket fob also works flawlessly except for the single issue requiring it to be held near the Start button.  The suggestion that the fob antenna may be the culprit sounds valid to me.  I also wonder whether the people who have $550 to gain every time a Lexus owner walks into a dealership and asks for a replacement fob may be part of the answer.