One problem related to power assist brake has been reported for the 2002 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Toyota Prius based on all problems reported for the 2002 Prius.
Brake light came on frequently. Dealership reports brake accumulator booster assembly leaking. Dealership told me it was a safety issue that could cause brake failure. Dealership replaced the brake booster, accumulator assembly.