Do I have to have a dealer reprogram my car after replacing the battery

 

No. Just change the battery yourself.

 

My Audi S4 and my old BMW X3 required dealer programming on new batteries. Not sure on Lexus...

 

Since this is posted in the 4RX section, why would you need to replace the battery already?

Dealer should be tossing one in for free.

 

Sorry. I read the post too fast. I thought you meant reprogram the key fob when you're replacing the battery of the key fob.

 

You will probably lose at least some settings. What I have always done is attach my Battery Tender (trickle charger) onto the 2 battery cables before they are removed from the battery. This way the car's electronics continues to see some voltage. You remove the Battery Tender once the battery cables are tightened onto the new battery. Again, this is if you are talking about replacing the battery under the hood, not the battery in the key fob (which doesn't require reprogramming after replacement).

 

What a good idea....never thought of that!

 

Years ago, a device was sold that took a small 9v battery and plugged into the cigarette lighter to help save settings when the underhood battery was replaced. Not sure if it ever worked since the power output was tiny and the cigarette outlet usually was not live on most cars when the engine was off.