I have a lexus ls430 2002. The key fob doesn't seem to be recognised by the car. The car does not flag up key not detected. The key fob opens and closes the doors. The battery is new in the key fob and the battery in the car is fully charged. It worked perfectly yesterday, but when I tried to start it today the switch does not turn.

 

Did you try moving the steering wheel a little bit first?

 

Maybe you pressed the button under the steeringwheel, that shuts down all keyless modes?
then the car starts only, when you stick the fob in

 

Also, if you tried to reset the tire pressure switch and hit the wrong button. I ALWAYS do that then cuss a lot because its so hard to reach.