One problem related to brake master cylinder has been reported for the 2001 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Toyota Sienna based on all problems reported for the 2001 Sienna.
While driving at slow speeds and depressing the brake pedal, the deceleration is almost zero. Pressing harder on the pedal does nothing to increase the deceleration. This has happened numerous times. I have had the vehicle into the shop several times and nothing could be found. I have repalced the master cylinder with no change. Crashes were averted in some cases by inches.