Without this car in the shop with full test gear I'm going to say it's time to try some other fob. It's hundreds and not thousands.
One of the troubles as cars age is that things like this can happen and we just use the key to lock it up. The convenience factor is of course lost but repairs on such old cars are always a test of how much we'll invest.
-> When I get into such troubles I call the car maker's support line directly. Skip the dealer and head for the regional headquarters. Do not ask them how to fix it directly but talk about the issue and ask if they've heard of this issue. They get enough calls asking how to fix stuff so we want to avoid that.
I have a 2007 Lexus is250. I believe it has electric problems so I went to dealer they said they have to remove the dashboard to check all the electric wiring, which will cost me more then a thousand dollars. So I decided not to.
The problem is with the key Fob. I replaced the key fob battery and the car battery have more then 12v reading.
Right after when I turn off the car, the key fob will work for less then 30 seconds. So right after i turn of the engine I have to lock the car immediately otherwise it won't lock via key fob. Which means when i turn off the engine it turn off everything, in modern car when we turn off the car it still uses some electricity to keep all the computers and key fob alive.
In my case it does not stay alive. That's why i think my key fob is not working because my car doesn't draw any electricity when I turn the engine off.
Anybody have any solution to fix this issue? I appreciate your response. Thank you.