2011 Toyota Prius brakes problems

Filed Oct 27, 2026 · Brakes · AL

I was driving the vehicle and a bunch of dash lights came on regarding traction control and stability and lost all brakes and almost caused an accident! The codes thrown showed a fluid level indicator and a leak in accumulator

Filed Oct 1, 2026 · Brakes · TX

I was driving on the highway when my 2011 Toyota Prius started beeping repeatedly, and as I approached the red light, my brakes were not operational. My car completely passed through the red light, narrowly missing what could have been a fatal accident for me and others on the road. I had to navigate to the furthest right lane, almost getting hit by others due to my speed and inability to stop my car. I was going at 50 mph through the intersection, and had to gradually lower my speed in the righthand lane. The Toyota dealership confirmed the issue with my brake accumulator, with a C1391 code. The only warnings were the brake light in the moment and the repeated beeping noise. To stop the car I had to slow down with my foot off the gas, and use my emergency brake once I could.

Filed Sep 30, 2026 · Brakes · CA

2011 Toyota Prius with approximately 134,000 miles. The brake actuator/master cylinder has been diagnosed as malfunctioning and failing to maintain hydraulic pressure. The brake booster pump initially began cycling approximately every 10 seconds while the vehicle was in READY mode, stationary, and without the brake pedal being applied. The cycling subsequently increased to approximately every 3 seconds. The affected components remain installed and are available for inspection upon request prior to repair. Because this condition involves the braking system, I am concerned about the potential for reduced brake assistance or further brake system failure, as well as excessive wear on the booster pump from repeatedly restoring lost pressure. I have limited use of the vehicle while arranging repair. An independent repair facility reproduced and diagnosed the problem. Diagnostic testing produced DTC C1391 (Accumulator Leak Malfunction), and the brake actuator/master cylinder was diagnosed as the source of the pressure loss and recommended for replacement. The vehicle has not been inspected for this condition by the manufacturer, police, or insurance representatives. The primary symptom was increasingly frequent brake booster pump operation without brake application. Toyota previously established a Customer Support Program addressing certain brake booster/brake booster pump assembly failures in 2011–2015 Prius vehicles, including conditions associated with C1391. The vehicle is below 150,000 miles but outside the program's time limitation.

Filed Sep 14, 2026 · Brakes · VA · crash

I am filing this complaint to report an active, severe safety defect involving a sudden, un-warned loss of power braking assist due to a failing factory brake actuator/booster pump assembly. My vehicle is exhibiting the exact internal hydraulic seal failure, pressure drop, and audible hissing/sipping sound outlined in Toyota's prior technical service bulletins. Because the onboard ECU computer only triggers warning lights once a complete, catastrophic failure threshold is met, the system is currently masking the defect from the dashboard. However, the physical hardware is actively failing, requiring the high-pressure pump to run constantly to maintain braking pressure. This component failure dramatically increases stopping distances and presents an immediate, unreasonable risk of a crash. Toyota previously acknowledged this widespread manufacturing defect via Customer Support Program ZJB (20TA02). However, because Toyota chose to manage this critical safety hazard through a time-limited warranty extension rather than a mandatory safety recall, hundreds of thousands of vehicles are now left with a catastrophic braking hazard because the consumer coverage expired in 2022. I urge the federal safety agency to open a formal defect petition review to investigate these post-warranty failures and mandate a retroactive safety recall to protect the public.

Filed Aug 10, 2026 · Brakes · IA

Vehicle Information: 2011 Toyota Prius, 144,000 miles. Component: Hydraulic Service Brakes, Electronic Stability Control, Anti-lock Braking System. Description of Incident: While driving at normal speeds, the vehicle suddenly experienced a severe reduction in braking capability. The dashboard simultaneously illuminated the Brake Warning Light, ABS Light, and Slip/Traction Control Indicator Light. The brake pedal immediately became soft, spongy, and squishy, requiring significantly increased physical foot pressure and a vastly extended distance to bring the vehicle to a stop. Upon inspection, the brake fluid reservoir remains completely full, but the brake booster pump under the hood cycles and buzzes rapidly every 10 seconds while stationary. A diagnostic scan confirmed trouble code C1391 (Brake Actuator Internal Leak). This indicates a severe internal hydraulic pressure bleed inside the braking module. [SEE ATTACHED] This is a known, widespread manufacturing defect previously documented under Toyota Customer Support Program ZJB. The manufacturer has refused to remedy this life-threatening safety defect because a 10-year calendar threshold has passed, despite the vehicle being well under the 150,000-mile limit established by the manufacturer. The vehicle currently poses an immediate safety risk to occupants and the public.

Filed Jul 26, 2026 · Brakes · TX

Every time I'd press the brakes there'd be an audible "click" noise and then when taking my foot off the brake it'd sound like a manual tire pump being pressed... kind of like air filling / hydraulic sound. This worried me (I don't mess around with brakes). One other thing that would happen is if I pressed the brake hard enough, the automatic braking system would kick in. The Toyota dealership claimed they couldn't hear anything and there were no warning lights so I took it to a reputable local mechanic. They diagnosed it as a bad ABS Actuator / Brake Booster and said it's common with this year of Prius. They also said it was good I brought it in now because it was not severe enough to totally fail (which could have caused an accident) but there was evidence of degradation and they also said the issue was causing sufficient brake fluid to not get where it needs to be.

Filed Jun 26, 2026 · Brakes · CA

Vehicle Information: Year: 2011 Make: Toyota Model: Prius Mileage at Failure: 58,769 miles Date of First Use: February 20, 2012 Complaint Description: As I was driving on the freeway, my 2011 Toyota Prius brakelights all came on. I pulled off, had it towed to nearest mechanic, who diagnosed a failure involving the brake booster, brake actuator, and ABS system at only 58,769 miles. The vehicle was diagnosed with Diagnostic Trouble Code C1391 (Abnormal Leak of Accumulator Pressure). According to my mechanic, the condition is caused by an internal brake fluid leak within the brake booster assembly with master cylinder. The recommended repair includes replacement of both the brake booster assembly with master cylinder and the brake booster pump assembly. The estimated cost of repair is approximately $4,100. This concerns me because the brake system is a critical safety component, and I believe such a failure at fewer than 60,000 miles is highly unusual and may pose a safety risk to drivers and passengers. Toyota previously issued a Warranty Enhancement Program for this issue, but my vehicle was denied coverage because the program expired on August 31, 2021, and the secondary coverage expired on February 20, 2022, ten years after the vehicle's first use date. Toyota declined any out-of-warranty assistance despite the vehicle's exceptionally low mileage. I am submitting this complaint so that this incident is documented as a potential safety concern involving premature failure of the brake booster and ABS system components on the 2011 Toyota Prius.

Filed Jun 18, 2026 · Brakes · NC

Shortly after purchasing used last year I had my brake, traction control, ABS, & TPMS lights come on when stopping at a stop light all at once. I went and had it scanned and no codes showed up. I hear a buzzing from the brake actuator/ brake pump every 15 seconds. This all has been going on for almost a year now. Over the weekend a loud buzzing warning alarm came on that will not turn off. I had it checked out and was quoted around 3500 to repair.

Filed Jun 16, 2026 · Brakes · SC

The ABS actuator (brake booster) went out suddenly. It is 100% available for inspection. It is being towed to M&M Auto Repair in Gaston SC. I was not sure if the car was going to stop when I was trying to figure out what was wrong. The car was acting like it wasn't going to stop until a few seconds later. People online have had a similar problem as me with prius models around my year to 2015. And it was a problem confirmed by the dealership. The component has not been inspected. Only diagnostics were ran. The ABS system light came on. But it would disappear for a long time then come back. So I thought it was a computer error for the longest until it proved to not be one. Because the brakes were working just fine like normal. Other than that, the light itself was playing peekaboo with me, making me believe that it was a computer error since the brakes were working just fine. Then on monday, the car started beeping excessively and the brakes were not working suddenly after being fine over the weekend....with no issues.

Filed Jun 2, 2026 · Brakes · MO

There is a known problem with the brake booster and skid control that was a part of an customer support extended recall program. Our Prius has very low miles (less that 60,000) so the issue didn't trigger for us until recently. Unfortunately, we are out of the extended recall program of 10 years or 150,000. This doesn't seem fair since it is a known and documented issue from Toyota. Unless we fix the issue, we are at risk of losing braking control. All brake lights on the dash are on and it is currently in the shop.