2015 Toyota Prius

omponent/System Involved: SERVICE BRAKES, HYDRAULIC ⸻ Make: Toyota Model: Prius Year: 2015 Mileage: 155,470 VIN: [XXX] ⸻ What happened: My 2015 Toyota Prius is experiencing brake failure symptoms related to a known defect addressed in Toyota’s Warranty Enhancement Program ZJB. The vehicle has triggered DTC codes C1256 and C1391, which indicate failure of the brake booster and master cylinder — a problem widely reported by Prius owners. The defect causes decreased brake effectiveness and increased stopping distance. My Prius is just 5,470 miles over Toyota’s 150,000-mile coverage cap, and despite confirming the exact codes, the dealership refused to repair unless Toyota pays first. Toyota Corporate opened Case #[XXX], but has not offered a resolution. This is a safety-critical issue that Toyota acknowledges in internal service bulletins, but they are denying assistance based on a technicality, despite my vehicle having the exact failure their program is designed to address. I am filing this complaint because I believe Toyota is avoiding responsibility for a dangerous manufacturing defect affecting braking performance and safety. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Failure of brake pump and brake cylinder assembly system, resulting in reduced braking ability and stiff brake pedal. Per Toyota's diagnostic: trouble code C1391 is present, abnormal leak in accumulator, replaced brake ABS actuator assembly, along with brake master cylinder, and bleed the brake hydraulic system. No warning lamps or safety indicators prior to failure. Upon failure (while on freeway going 50+ MPH) the ABS, Brake, and traction control warning lamps illuminated. The failure resulted in no accident or injury, however it did occur while on the freeway going freeway speeds, and resulted in difficulty in braking, which was dangerous. Took Prius into Toyota dealer for diagnostic and repair, was told that part was known to fail in this model of Prius, and had a manufacturer designated extended warranty for 10 years or 150,000 miles. However, despite prius being under 150,000 miles, it passed ten years since purchase in march 2025, meaning I had to pay in full for the repair ($3,631.96). The car gave no indication of needing the repair until the day of the failure, which was on June 18th 2025. If the vehicle had given some prior indication of brake pump system failure or fault I would have had it repaired prior to the warranty expiration, but it did not, leaving me to pay out of pocket for a failed part that Toyota is at fault for making prone to failure.

Brake booster failed while driving down the mountains back from big bear. Nearly wrecked several times, had no idea why my brakes weren't working properly. Go to AutoZone to scam the code, and I got the dreaded ABS failure. Sadly the extended warranty for this known issue from Toyota conveniently expired 2 weeks before the failure. Toyota should be held accountable and pay for my repair, that O did myself. Parts cost me $1800, plus a day off from work I had to take. Atrocious situation, Toyota should be ashamed.

While driving my 2015 Toyota Prius, the brake pedal became extremely stiff and hard to press. I was on the way to the dog park with my dog in the back seat when I had to press down very hard just to slow the car at a traffic light. It felt like I was stepping on a rock. The brakes barely engaged, and I had to use far more force than normal to get the car to stop in time. When I hit the brakes, they finally caught hard and suddenly and my dog went flying off the back seat and landed on the floor. She’s fine physically, but now she’s terrified of getting in the car at all. It was scary for both of us and felt totally unsafe. If I had been going just a little faster or if someone was walking across that intersection, it could’ve ended badly. I later found out this issue is tied to a known defect with the brake booster and accumulator system, specifically related to code C1391. Toyota even acknowledged this problem in a Customer Support Program (CSP ZJB/ZKK), but they refuse to help because my car is slightly over the mileage limit. That doesn’t change the fact that this is a serious, dangerous failure that affects the driver’s ability to stop safely. Toyota should be forced to take responsibility for this failure before someone gets seriously hurt.

Toyota Hybrid Brake Problems 2015 Toyota Prius I took to my dealership Jim Ellis Toyota in McDonough GA. I was told that my brake master cylinder & brake booster pumps vehicle has failed. I experienced my brakes locking up, causing the vehicle to unexpectedly lunge forward or failing to engage when the brake pedal is depressed. On [XXX] my ABS, Brake, Traction lights came on out of nowhere. I tried taking it to my dealership in April to Jim Ellis, Toyota of McDonough for the lights, the one lights being on. I took it there around 8 o’clock in the morning and then there was a very rude and disrespectful service person by the name of Victoria who told me that they would not be able to see me and told me that I needed to leave because I didn’t I have an appointment. This is a Dealership that I purchased this car phone in 2018 and I have been taking my car to Jim Ellis Toyota of McDonough since 2018 to get regular oil changes and other maintenance for my car. Such as things my brakes replace my front and the back brakes have my battery please and come several times out of the year to get a oil change because I have part of what they consider a lifetime oil change on my car. Also, I had a Warranty whole time that I have been taking my car to the dealership they never once brought to my attention that there was a known recall for the brakes booster. It wasn’t until I took my car to dealership on Friday 5/30/25 that I was advised that this was a known issue for 2010-2015 Toyota Prius Jim Ellis dealership knew about the problem and failed to make repairs when I spoke with general manager Lorenzo Smith he advised that past the recall timeframe and my warranty has expired. Jim Ellis dealership knew their were known issues and hid the issue I refuse to write the wrong by making the repairs to my vehicle. They’re trying to charge me over $3200 in repairs when I spoke with the general manager, he advised me that they didn’t make the repairs because my vehicle vin number. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFOR

I own a 2015 Toyota prius, purchased new and put in service December 4th, 2014. Car is well maintained. On May 10th, 2025 The Brake booster pump and assembly failed. Has internal leak. I had the dealer confirm this. Lights on the dash, computer code c1391 ( abnormal leak in accumulator, Rec replacement of brake booster and pump) and brake booster pump is pumping every 3 seconds from internal leak. Brakes are now at 50%. Soft. The Pads and shoes are perfectly fine. It’s the brake booster pump assembly. Toyota issued instead of a recall, which would have been the right thing to due considering its long history of these over multiple years failing, just a customer service letter. 10 years or 150,000 miles, which ever comes first. Mine failed at 10 1/2 years. Now I am stuck with a $3,000 bill which I can not afford, to replace the Brake booster pump and assembly. Toyota completely knows of the issue and side stepped having to issue a recall on this very well know problem.

Left our house and as we were driving out of our neighborhood the ABS and Brake lights came on. We looked it up in our book and couldn't find anything concrete to go on. Drove straight to Auto Zone and their test came back most likely Brake booster or master cylinder. While looking it up, we read several stories people had posted saying this was a defect with 2012 - 2015 Toyota Prius' and to write to you and tell of the incident. I put my Vin # in and it doesn't show any recalls about this. Any feedback would be helpful. Thank you!

Car feels like it lunges forward while braking over bumps. I have learned this is a known manufacture defect with the Brake Booster and Brake Actuator which Toyota is refusing to replace outside of 10 years from manufacture date. This is a critical safety item and failure can result in loss of brake power. Most owners do not know this part even exists until failure has happened already.