2011 Toyota Prius: soft or spongy brake pedal

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 Jan 31, 2025 · Brakes · CA

While driving on the interstate, the "brake", "TCS", and "ABS" lamps lit up. The brake pedal was stiff and couldn't be depressed. The vehicle initially did not decelerate while attempting to push down on the brake pedal. While maneuvering off the interstate on to the exit lane, the pedal remained stiff however, the vehicle did begin to decelerate. Critically, the amount of time needed to bring the vehicle to a stop was significantly longer than normal. This brake failure could have resulted in a catastrophic, life threatening and/or deadly accident. The DTC associated with this brake booster and pump failure is C1391 which is referenced in TSB-0024-19. This is a known problem that exists in Priuses manufactured between 2010-2015 and addressed by Toyota with CSP(s). The CSP takes a reactive approach to this serious safety concern as owners who "have not experienced the condition described" were informed that "there is no action necessary at this time". The extended warranty of 10 years or 150,000 miles is not applicable to countless drivers who are experiencing this failure caused by "internal malfunctions" outside of this arbitrary time/mileage frame. A letter was sent to the federal safety agency on 9/19/19 by the president of Claremont and Capistrano Toyota to petition for the initiation of a Defect Investigation regarding this issue. The letter notes that this brake defect is "causing crashes that are injuring people- and Toyota is mishandling it". The advisor assigned to this repair estimated that they see this issue 1-2 times a month and increasingly, drivers are not covered by the CSP. Toyota is failing to take a proactive approach to this dangerous safety issue by telling owners to essentially wait and see if they experience this failure and then failing to take responsibility for said costly failure should it occur outside of their arbitrary time/mileage frame. This approach to safety is egregious, irresponsible, and unethical and it is putting countless lives at risk.

Filed Jul 17, 2024 · Brakes · AZ

No incident, 3⚠️ Light started recently, traction control, ABS, and Brake light, 07/15/2024. Big O tire did oil change, inspection, claims brake are ok, warning ⚠️ lights comes on and off intermittently, causes brakes when on to become soft pedal when stopping, I consider a defect of workmanship by Toyota on this 3011 model possibly others l. Thank you for your time

Filed Jan 22, 2024 · Brakes · CA

While driving the car I had three lights turn on the dash simultaneously. The parking brake light, traction control light, and ABS light. The brakes worked but felt spongy and not as responsive as normal. I had it checked out and it has code C1391. The recommendation is to replace the brake booster pump. I was quoted over $2,000 for the repair. There was a Toyota Customer Support Program ZJB that addressed this exact issue. It expired two years ago, and I am now stuck with the repair costs. I believe Toyota should have notified me of this potential danger and/or inspected the vehicle. I meet all the requirements of the bulletin, but it has expired. I reached out to Toyota, and they would not offer any assistance.

Filed Jul 17, 2023 · Brakes · FL

Dear Mr; I own a 2011 Toyota Prius, and this week my brakes failed while driving down the highway. The ABS and Break lights and the ESP warning light on the instrument panel come on. The brake pedal is hard and has an intermittent hum in the engine area. The scanner gave the code C1391 / ACC PRESS abnormal leak error. I want to file a formal claim against Toyota for the failure of my car's brake system and request repair/replacement of my car's brake system. --------------------------------------------------------------------------------------------------------------------------------------------- What component or system failed or malfunctioned, and is it available for inspection upon request? BRAK SISTEMS / YES, IS AVAILABLE FOR INSPECTION. How was your safety or the safety of others put at risk? IT WAS DIFFICULT TO BRAKE / THE CAR WAS DEVIATED WHEN APPLYING THE BRAKE / I LEFT THE ROAD DUE TO THE RISK OF A COLLISION BY NOT HAVING THE ACTIVE BRAKING SYSTEM. Has the problem been reproduced or confirmed by a dealer or independent service center? YES / INDEPENDENT SERVICE. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? NO. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? NO

Filed Apr 18, 2023 · Brakes · 9,000 miles · NC

The contact owns a 2011 Toyota Prius. The contact stated that while operating the vehicle, the emergency brake and traction control warning lights remained illuminated, and the stopping distance was extended while depressing the brake pedal. The vehicle was taken to the local dealer who diagnosed that the hydraulic brake booster was faulty and needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure and informed the contact that the vehicle was no longer covered under the manufacturer extended coverage for the failure. The contact stated that over the years the vehicle had experienced failures which included brake pedal stiffness and unintended acceleration after driving over bumps in the roadway. The failure mileage was 9,000. The VIN was not available.

Filed Feb 17, 2022 · Brakes · FL

ABS actuator pump won't stop running, ABS light comes on, and brakes are spongy.

Filed Feb 16, 2022 · Brakes, Driver assistance · 90,000 miles · CA

The contact owns a 2011 Toyota Prius. The contact stated while driving 50 MPH on the highway, the brake pedal was depressed but failed to respond. The contact depressed the brake pedal harder and the vehicle almost came to a complete stop. The ABS warning light, the brake warning light, and the traction control warning light illuminated. The contact stated that she exited the highway and was able to continue to drive by slightly depressing the brake pedal. The vehicle was taken to the dealer where it was diagnosed that there was an internal malfunction of the brake booster and the brake booster assembly pump. The vehicle was not repaired. The contact contacted the manufacturer and inquired about assistance with repairing the vehicle under an unknown customer satisfaction program. The manufacturer informed the contact that the failure was not a safety issue and they could not assist as the customer satisfaction program had already expired. The failure mileage was approximately 90,000.

Filed May 29, 2021 · Brakes · TX

Around 100,000 miles the brake system has been sluggish and it appears the ABS system is failing. Currently the car has 118,617 miles and constantly exhibits sluggish and spongy braking. Hitting a pot hole or any type of bump while pressing the brakes can cause the ABS to light up temporarily and the brakes feel as if they release for 1 second and re-engage. When pressing the brakes there is a popping/air-like sound in the brake system constantly. Bleeding the brakes did not solve this issue. Through research I have discovered this is a complaint of many Prius owners about their brake actuator. It is a $1700+ part that, if fails, will cause the entire brake system to fail.

Filed Mar 6, 2020 · Brakes · 111,100 miles · FL · crash

A few weeks ago my brake and ABS lights came on and my brake pedal changed and became spongy. Since I was still able to brake, I kept driving the car and became used to the spongy pedal. Then the other day I was returning home from work when the car in front of me suddenly hit his brakes. I had to quickly hit mine as well and the brakes locked up sending the car sharply to the right and I crashed into the guard rail causing $1500 worth of damage. I picked up the car today after having the damage repaired but I still have the same problem.

Filed Sep 13, 2019 · Brakes · 164,643 miles · IL

I have an early year 2011 toyota prius, the break booster and master cylinder assembly work intermediately. Sometimes it shows errors with lights illuminated on the dashboard and brakes have a lot of play and are spongy and other times they work perfectly normally. The vehicle was in motion and when I went to use the breaks in a traffic situation they ended up hardly working putting myself in a higher risk for a collision and putting my life endanger.

Filed Dec 18, 2018 · Brakes · 104,000 miles · FL

Takata recall my 2011 prius has an issue where the brake becomes spongy at random while driving under normal conditions. The brake, ABS, and traction control lights all illuminate simultaneously. After resetting the computer, the issue comes back within 10-30 minutes of driving at random. Toyota told me it is a $3,000 fix and there is no recall for my year. My car has 110,393 miles.