One problem related to brake disc caliper has been reported for the 2007 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2007 Toyota Sienna based on all problems reported for the 2007 Sienna.
Rear brakes wore out at 21k miles even though front brakes were fine. Dealer blamed it on corrosion even though the vehicle was only 15mos old and spent all winter in florida. The front brakes show no sign of wear or corrosion!. Dealer charged for pads and rotors which did not fix the problem. Eventually replaced calipers which did fix the problem. I feel that the wearing out of only the rear brake pads is very unusual and was due to original manufacturer calipers. The end result (brake failure) was unanticipated and could have resulted in handling problems and an accident.