Well potato is because i made it that way. I drive around 100 miles a day with the prius and all I am loosing is the regenerative brakes. If i reset the code I can use them again but any more than 50% brakes and it comes back on. Car is still drive able and I will drive it until I figure out how to fix the problem. If n one really knows how to fix then I will replace that problematic wheel cylinder . ADVICS I think is the original manufactorer and they are available for Under $20
