Buying a 2009 but worried now...

There are a lot of old timers and experienced Prius mechanics that have experienced just about every common failure, and quite a few uncommon Prius failures. All of these items have been covered in great detail on this site. For example, on the First Generation Prius there are known issues with the gas pedal sensor, 2001 battery leaks, quick wearing tires, and some rare transaxle failures. None of these are dangerous and only apply to Prius's before 2004.

On the present Prius, there were some things like 2005 Prius display problems and plastic dash trim issues. The 2006 models and later are totally problem free. A true brake problem has not surfaced here that I can remember.

Every now and then we hear of "brake problems" that have nearly always to be traceable to two sources:
1) The ABS, Traction Control, or VSC activated and the drivers were not use to these features. As a result PriusChat gets a lot of posts asking "What is wrong with the Prius brakes" and after much quizzing we find out that the problem occurred on things like a wet railroad track crossing, a gravel pit, etc. The bottom line is that on the rare occasion when the brakes are hit really hard or a really slippery condition is encountered, the Prius safety systems on the brakes are going to activate to keep the car as safe as possible in these extreme conditions. This automatic brake activations really is unusual when first experienced, alarming a driver already highly stressed. If a real brake problem does occur, a lot of indicators light up and the causes are recorded in electronic memory.
2) Certain web sites just make up stuff.

 

Toyota assembly quality vs Big Three. That's an entirely different thread topic, for the most part the horror stories of empty pop bottles in door panels just don't happen to Toyota or Honda vehicles

However, if anything is even remotely iffy with the Prius braking system, the dash will light up like a christmas tree.

I'm not going to get into any servicing details, but long story short: the only way to service - bleed - the brakes on a Prius is with the factory approved scantool interface. The scantool software can command the boost pump and various solenoid valves

There are many function checks applied to Prius cars when they are assembled. The braking system - regenerative and friction - is one such check

 

Brake problems??? Nope... we have 2 prii...a 2004 with 111000 miles on it and a 2009 with 1000 miles...no brake problems on the 04 at all...still have about a 1/4 of the brake pad left on front disks at 111000 miles...thats all mostly city stopping and stupid red lights that the traffic engineers that set them havent got a clue...but anyway...no problems with brakes at all...period...

 

The first time I braked while moving across a wide painted white patch on a rain-slicked roadway, the automatic stability control/brake control DID feel freaky, I'll admit. However, as soon as I got OFF the paint patch, things were quickly back to normal.
I've also accelerated with a front tire sitting on a railroad track...
These CAN seem like weird "malfunctions" until you realize what's going on, and then it isn't quite so unsettling. It's just different technology than cars that do not have the VSC and ABS systems.