I have replaced front wheel bearings, rack & pinion (when the car had approx. 30,000 miles on it) and TIRES!!! I'm always buying tires - no matter how I inflate them! The best set of tires so far have been Nokian tires but now trying Hankook winter tires. Code 3191 has popped up several times (I've had the throttle body cleaned. New codes as of yesterday are P0420, P0440, P1636 - which I'm being told means I need a new catalytic converter at $1371.72!!!! I have 179051 miles on my 2002. All of a sudden I'm finding lots of rust (the car had been rust-proofed) and have found that several other 2002 Prius in the area have rust in the exact same place - over the windshield in 2 places. I love my Prius and it will be a sad day when I have to put her down!