Just got the dreaded "error 3" message on my 2007 SC430. Followed the advice of Wuzzy & Mortarman who posted on IS 2001-2005 thread and disconnected negative battery lead for 18 minutes.
CD changer reset and now all is well. I had to reset radio stations & clock.
After disconnecting battery the seat memory settings stopped working. I found the fix on this YouTube video. I am grateful for the help I receive as a member of this forum.