After 120K miles and 11 years of use, my Prius 3 brake booster pump failed while I was driving. The warning lights came on, including the ABS and brake lights. My brake felt strange, and I had to finish my drive to the dealership keeping a large driving distance so the brakes would work in time. I was advised that this was a result of a C1391 error and that the brake pump part is only covered under extended warranty for 10 years. The advisors at the dealership said it is extremely common for cars to come in with this problem just after the warranty period has ended. I have spoken to other Prius user who have complained of the same issue and are considering a class action lawsuit because this safety issue is so common.