2012 Toyota Prius Complaints

My Brake Booster/Actuator failed on me while on the freeway with out any warnings. It made it really hard to stop the car. I didn't find out what it was untill I took it into a repair shop and they told me it was the Brake Booster/Actuator.

The vehicle is experiencing a suspected brake actuator / brake booster failure. Multiple warning lights appeared simultaneously, including ABS, Brake, Traction Control, and Master Warning lights. The vehicle produces a frequent buzzing noise from the brake system, especially at low speeds or when stopped. The noise occurs repeatedly when pressing the brake pedal, indicating the system is struggling to maintain hydraulic pressure. This condition raises serious safety concerns because it may reduce braking performance and increase stopping distance. Brake system failures present a significant risk to vehicle occupants and others on the road. After researching the issue, I learned this appears to be a common failure in Toyota Prius vehicles of similar model years, and Toyota previously issued extended warranty coverage for the brake booster/actuator assemblies. However, many vehicles now exceed the coverage limits despite the safety nature of the defect. I am submitting this complaint...

Vehicle check engine code C1391 (Antilock Brake System - abnormal leak in accumulator) came up on 2/5/2026. Recommended repair is to replace the Brake Booster Pump and Assembly, Brake Booster - over $1000 in parts alone. This WAS covered by an Extended Warranty by Toyota (10 years / 150K miles). I only have 120K miles at this time but am past the 10 year mark. However, it seems that this part will fail in every Prius given time and encourage NHTSA to monitor these failures and hold Toyota accountable to address post the 10 year / 150K mile mark.

Vehicle: 2012 Toyota Prius Mileage: Approximately 217,000 miles While driving normally in traffic, the vehicle experienced a sudden and unexpected brake system failure. Multiple warning lights illuminated simultaneously, including the red BRAKE warning light, ABS warning light, traction control light, and warning symbol (!). Shortly after, the vehicle began emitting an audible warning/beeping, and there was a sudden loss of power brake assist. The brake pedal behavior changed abruptly: the pedal became very soft initially, then became suddenly hard halfway through travel, This failure occurred while approaching another vehicle in traffic, and I narrowly avoided rear-ending the vehicle in front of me. The unexpected loss of brake assist created an immediate and dangerous situation, as the vehicle did not decelerate as expected when the brake pedal was applied. Due to the seriousness of the brake failure and safety risk, the vehicle was removed from service and towed. This incident...

My 2012 Toyota Prius plug in hybrid had just passed state inspections and was even looked at by a dealership a year ago with no reported issues. I brought up a whirring issue at the dealership when breaking but the dealership said that’s normal for a hybrid. In a matter of minutes while driving, the traction light, brake light, and ABS light came on as well as a groaning, whirring sound when breaking. Over time, the breaks failed and I could not stop the car, almost causing a wreck because I could not stop without putting all my body weight on the break pedal. When taking it to the Toyota dealership for a whole diagnostic, they said it was a break actuator and break booster failure that is known to happen with Prius’s. They quoted me $3000 for a repair and then marked my breaks as yellow not red on their sheet implying I could still drive it despite the dangerous situation of driving without functioning breaks. When looking into it, this seems to be a known and common problem with Priu...