Service Brakes Problems of Toyota Prius - part 1

The contact owns a 2012 Toyota Prius. The contact stated that while driving 65 mph and depressing the brake pedal there was a buzzing sound coming from the vehicle and the brake warning light illuminated. The contact stated that after inspecting the vehicle, the brake fluid level was very low. The vehicle was taken to a service center where it was diagnosed and dtc: c1391; was retrieved. The contact was informed that a leak in the brake accumulator had caused the brake master cylinder and hydraulic power brake accumulator to fail and needed to be replaced. The vehicle was scheduled to be repaired by the service center. The manufacturer was made aware of the failure via telephone. The contact stated that the manufacturer was aware of the failure and offered an extended warranty to cover the repair. However, the part needed to be replaced. The failure mileage was approximately 81,239.

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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 NHTSA to open a formal defect petition review to investigate these post-warranty failures and mandate a retroactive safety recall to protect the public.

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The vehicle is experiencing a critical failure of the brake actuator and booster pump assembly. The dashboard currently displays multiple warning indicators: abs light, traction control light, and the brake system warning light (master warning "!"). Symptoms: mechanical failure: the internal high-pressure accumulator is failing to hold pressure. The electric brake booster pump is heard cycling every 10-20 seconds even when the vehicle is stationary and the brake pedal is not depressed. Loss of braking safety features: the system has disabled regenerative braking and anti-lock braking (abs), causing significantly increased stopping distances and a “spongy" brake pedal feel with diminished braking response. Predictability of failure: this failure matches the exact symptoms described in Toyota's customer support program 20te07 (and previously zjb), which acknowledges an internal defect in the brake actuator. Safetv risk: the sudden transition from power-assisted braking to manual hydraulic braking during a drive creates an immediate safety hazard. As the pump motor continues to cycle excessively to compensate for the internal leak, it is at risk of total thermal failure, which would lead to a near-total loss of braking assist while the vehicle is in motion. Despite the vehicle having only 75,689 miles (well under the 150,000 mile limit acknowledged in Toyota's support programs), Toyota has declined to provide assistance because the vehicle has surpassed the 10-year age mark. Toyota is wrong in not providing support for vehicles whose critical components such as brakes shouldn’t experience catastrophic internal failure at 75,689 miles, regardless of the vehicle's age.

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I am reporting an active, severe safety hazard regarding the braking system on my 2015 Toyota Prius ( mileage: 79,000). The vehicle has been officially diagnosed by Toyota culver city with diagnostic trouble code dtc c1391, confirming an internal failure and lack of pressure within the brake booster/actuator assembly. This component defect causes an immediate compromise to the vehicle's braking efficiency and hydraulic pressure, causing a sudden loss of braking power and significantly increasing stopping distances. Toyota was fully aware of this dangerous defect and initiated customer support program zjb to address it. However, Toyota brand engagement center (case #260909002032) has explicitly admitted via recorded voicemail that they mailed the safety/defect notification only to a previous owner and failed to notify me. Because they did not cross-reference current registration data, I was never notified of the defect and was deprived of a preemptive remedy before their arbitrary 10-year calendar clock expired. At only 79,000 miles, this critical safety component has failed prematurely, creating an active hazard on public roads. Toyota is refusing to cover the $3,890 repair despite their documented failure to notify the current owner.

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The contact owns a 2012 Toyota Prius v. The contact stated that while driving 65 mph, brake fluid was leaking from the vehicle. While driving over 45 mph, the brake pedal became firm, requiring the driver to exert extra force while depressing the brake pedal; the brakes failed to respond as intended. Additionally, a burning and toxic odor was present during the failure. Multiple warning lights illuminated on the instrument cluster, including the abs system, parking brake, brake malfunction, and electronic stability warning lights. In addition, the automotive brake system, brake pump, and pressure warning messages were displayed. The vehicle was taken to a local dealer, where it was diagnosed with a failed brake booster assembly after inspection. The dealer determined that the brake booster assembly needed to be replaced. The contact associated the failure with customer support program: 20te07. The contact was referred to the NHTSA hotline by a lawyer, and the contact had found a class action lawsuit related to the failure. The failure mileage was approximately 187,000.

Abs and brake light are on. Was on the freeway and when I pressed the brake the wheels got locked and the car made a 360 spin, it almost flipped over.

The brake booster assembly failed, as many of these models had before. A bunch of codes went off as I was driving and the brakes did not function properly. Toyota had an extended warranty for this which they discontinued last year and they would extend no good will towards the $4,000 repair.

While driving my 2014 Toyota Prius, the brake, abs, and vehicle stability/traction control warning lights illuminated. There was no crash, injury, or noticeable loss of braking before the warnings appeared, and there were no preceding symptoms. The vehicle was evaluated by mac haik Toyota in league city, TX, an authorized Toyota dealer. They diagnosed dtc c1391, “abnormal leak of accumulator,” and determined that the brake booster and brake booster pump/accumulator assembly require replacement. The dealer advised that the vehicle cannot be driven and is considered down. The vehicle/components are available for inspection upon request. My safety concern is that this is a brake-system malfunction serious enough that an authorized Toyota dealer has determined the vehicle cannot be driven. Toyota previously established customer support program zjb addressing internal malfunctions of the brake booster and brake booster pump assemblies in 2011–2015 Prius vehicles. Toyota’s documentation specifically identifies c1391 as a diagnostic code associated with this condition. My Prius has only approximately 102,000 miles, well below the program’s 150,000-mile limitation, but is outside its 10-year time limitation. The Toyota replacement part required to repair the brake system is now backordered with no known timeframe for availability. Because Toyota has advised the vehicle cannot be driven, it will remain out of service until the part becomes available. I am reporting this because a previously identified brake-system failure continues to occur after Toyota’s support period expires. I ask NHTSA to consider whether continued c1391 brake booster/accumulator failures in these Prius vehicles warrant further investigation or safety action.

The break pump for my 2013 Prius is going out and is a known issue with Toyota. I contacted Toyota and they have stated because it is past the extended warranty they can not repair it and aren't liable for it. I bought the car used and was unaware that it has been a known issue for years. The previous owner did not have it replaced as they were probably unaware as well. It is a highly unsafe issue and has caused my breaks to suddenly go our while driving recently with my toddler. It is also $3000-$5000 to fix it and is almost more than the cars value. I need help resolving this as it isn't "normal wear and tear" or a mileage issue. It is a known, very public defect that Toyota has admitted and I have been able to easily find information on all over google. The warning lights came on out of no where on the freeway today.

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Problem: brake actuator is pulsing the booster pump to keep running intermittently, 5-10 seconds. Console lights lit up for abs problem. Does not clear. Toyota dealership report: dct c1391 abnormal leak: monitored teh accumulator pressure and its not holding pressure. Pump keeps running. Rec[ommend] brake actuator and booster pump assembly [replacement]. ` servco Toyota dealership in hawaii report: submitted prior authorization request with Toyota hawaii warranty. Request denied for goodwill coverage on abs actuator and booster pump.

Subject: vehicle safety defect complaint / request for investigation review vehicle: 2010 Toyota Prius VIN: [xxx] component: electronic brake booster / pressure accumulator assembly dear administrator, I am writing to formally report a critical safety defect in my 2010 Toyota Prius regarding the electronic brake booster and accumulator pump assembly. This component exhibits classic failure symptoms—specifically a distinct puffing, ticking, and pressure-loss noise directly from the brake pedal mechanism—which points to internal nitrogen or hydraulic pressure leakage. This component was previously the subject of Toyota’s customer support program / safety recall (campaign zjb / d0h) due to fatigue cracking in the internal accumulator bladder. However, Toyota's arbitrary cutoff timelines have left me completely unprotected, even though the underlying engineering defect remains identical and poses an active, catastrophic threat to public safety. The real-world implications of this failure are severe: •daily risk to life: I am a self-employed small-business owner who relies on this vehicle daily to travel between clients across the greater [xxx] area. Because of this failing component, I experience profound fear every single time I drive that I will completely lose my brakes in heavy traffic. •financial barrier to remedy: authorized Toyota dealerships have quoted me several thousand dollars for the repair. Due to a 40% drop in my business income amid the soaring cost of living in [xxx], I cannot afford this repair, nor can I afford a rental car or alternative transportation. My car is my literal lifeline, forcing me to drive a vehicle with a compromised, safety-critical braking system. •unfair expiration of safety remedies: my vehicle was serviced by authorized Toyota dealerships twice during the active primary campaign window (on xxx at 36,675 miles, on 08/30/2019 at 41,238 miles), where recall status checks were routinely requested information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(.

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Component failed: brake actuator and accumulator on a 2010 Toyota Prius. It is available for inspection upon request. Safety: abs, traction, and brake lights turned on suddenly in the middle of rush-hour traffic, followed by a spongey, hard-to-press pedal. Braking distance and efficiency was greatly impacted, and driving to a safe turn-out was extremely dangerous as I feared the brakes would give out entirely at any moment. The problem has been reproduced and confirmed by a dealership. Unknown. Requested an inspection by the manufacturer but their "customer support program" for the brake actuator and accumulator expired 10 years after the car's production date. After speaking to both the dealership and corporate, they have informed me that there is nothing else they can do in regards to reimbursement or satisfying the complaint. The only symptom of the problem prior to failure was a periodic hissing noise coming from the brakes. When the car was brought in for the catalytic converter in late 2025, the dealership failed to diagnose any issue with the brake booster system at that time.

On xxx, I was driving my 2015 Toyota Prius with my family in the vehicle and approaching stopped traffic on dry pavement. An emergency vehicle was approaching from behind, so I began braking earlier than usual. When I applied the brakes, the vehicle did not stop normally. The front slowed/stopped while the rear of the Prius suddenly slid sideways toward the adjacent lane, bringing the rear passenger side dangerously close to another vehicle. Had I begun braking at my normal stopping distance, I believe a collision would have occurred. No crash or injuries occurred, but the incident was extremely dangerous. I drove the vehicle very slowly to purrfect auto services, [xxx], where the brake/abs system was diagnosed. I observed diagnostic code c1391. The shop has had the vehicle since xxx and has experienced repeated problems with used replacement brake-system components that were defective or would not function properly. The vehicle has remained unsafe to return to service while the shop works to obtain a properly functioning replacement part. I am reporting this because the sudden and unpredictable braking behavior created a serious risk to my family and other motorists. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

I purchased a 2013 Toyota Prius from a reputable dealership in omaha (o'daniel Honda). 5 days after purchase the abs, brake, and traction control lights came on in the evening. When I took it to the dealership the next day they had cycled off and the dealership couldn't find anything wrong. A few days later it happened again so I got into the dealer right away and they said Toyota had issued a service bulletin c1391 in 2019, and that I would have to replace the brake booster, brake cylinder, and brake pump assembly. I'm still fighting with the dealership to make this right, because they should have caught this during their inspection before putting the car for sale on their lot. The indicator lights keep cycling on and off. Something that effects the braking system should be a recall and not a service bulletin.

The contact owns a 2013 Toyota Prius. The contact stated that while driving 60 mph, the abs warning light illuminated. Minutes later, the vehicle started to brake and lurch forward with the accelerator pedal depressed. The contact stated that the vehicle spun out and crashed into the median. The contact’s chest struck the steering wheel, causing bruising and chest pain. The contact was managing the pain with analgesics. The vehicle was towed to an impound lot and was deemed a total loss by the insurance company. A police report was filed, but the report number was not provided. The manufacturer was contacted and was made aware of the failure. The failure mileage was approximately 140,000.

The contact owns a 2013 Toyota Prius. The contact stated that while driving at an undisclosed speed, the abs, traction control, and brake warning lights were illuminated. The contact pulled off on the off-ramp and became aware that extra effort was needed to depress the brake pedal. The vehicle was towed to the dealer and was diagnosed with brake booster and accumulator failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 120,000.

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.

Code dtc c1391 - abnormal leak of accumulator pressure. Internal failure of the brake booster pump assembly, preventing the system from maintaining proper hydraulic pressure. This means the brakes don't work, putting the driver's and passengers' lives at risk. This dtc c1391 code and problem were reproduced and confirmed by an independent service center who specializes in 3rd generation Priuses. There were warning lights that lit up when the brakes failed - the abs, traction control, and brake light all lit up but only after the brakes had stopped working. This is a known manufacturer defect but Toyota won't pay to fix it because they put a 10 year limit on first driven date or 150,000 miles. This Prius only has 100k miles but Toyota still won't stand behind their product even though they have admitted it was a manufacturing defect and they sold a defective product.

N/a.

Brake actuator had been making noises and it finally stopped working on 7/14/26. Thankfully my car was and stopped and parked. The car has 137k miles on it, one owner and no explanation of what caused this. There were no accidents, abuse, or failure to maintenance.

Brake lights icons stay on mechanic at Toyota dealership state need new brak master cylinder and booster.

The brake light, abs light, and traction control light is on. This was a known issue with Toyota Prius. They extended the warranty but failed to adequately notify user. I believe this is a serious safety issue and should be a recall as it affects the adequate stopping of a car, not just an extended warranty.

Code 1391 / power brake booster failure. Know defect by Toyota in which they extended warranty, vehicle is within mileage warranty but past the date warranty. Therefore Toyota will not assist in repairing. Very troubling in that this is a high risk recall or safety issue well known and instead of repairing extended. Repairs cost more than half the value of the vehicle and we are heavily reliant on this car and cannot afford 4k repair nor would sell knowing the saftey issue. Apparently there was notices sent for voluntary repairs in which I never received, had I received and reviewed I would have had repaired. My car had been to Toyota dealership and was never notified of this recall. Toyota offered voluntary programs (such as zjb or model-specific extensions like 21te01 for certain 2012–2014 Prius c vehicles) to replace failing brake boosters and pump assemblies.

Brake.

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Brake warning lights on, buzzing sound every 10 seconds. Likely a known actuator and master cylinder issue.

The traction control, abs, and emergency brake light came on. We checked and the code produced was c1391. There’s a humming noise every 10 or so seconds when idle. The humming noise is also present when braking. We did some research and this appears to be an issue with Toyota Prius. We called the dealership and were informed that this was not a known issue. Thank you.

Brake actuator assembly failure on a vehicle with 99,818 miles. Whirring sound when braking followed by lighting of several brake alert lights on dash including pcs and abs and others. The whirring noise has occured for several weeks, but the light indicators happened on 6/28/26. Toyota has an acknowledged customer support program (20te07) for this exact failure on this exact and Toyota declined to cover the repair. This vehicle is 14 years old but has well under 150k miles and Toyota will not honor claim though they clearly are aware of the safety hazard.

I am filing a formal safety complaint regarding a catastrophic brake component failure on my 2013 Toyota Prius, occurring at less than 83,000 miles. The vehicle’s brake master cylinder/actuator assembly has suffered an internal hydraulic pressure leak, causing the electric booster pump to run continuously to prevent a total loss of braking assist. This is a well-documented manufacturing defect that directly compromises passenger safety, drastically increases stopping distances, and threatens a complete loss of power assist while driving. Toyota explicitly acknowledged this inherent design flaw through its customer support program (zjb). However, they limited coverage to a strict 10-year expiration date from the first date of use. Because my vehicle has exceptionally low mileage and was driven gently, the component took longer to degrade, causing it to fail just outside Toyota's arbitrary time limit. Limiting safety coverage based on time rather than mileage penalizes owners of low-mileage vehicles for an engineered factory defect.

The vehicle experienced a failure in the braking system involving the brake booster/brake actuator assembly. The vehicle displayed diagnostic trouble code c1391, which is associated with a malfunction of the brake booster pump/accumulator system on this model. The failed component is available for inspection upon request. The failure created a safety concern because the braking system warning lights illuminated and the vehicle’s brake assist system may not function properly. A malfunction of the brake actuator/booster system could increase stopping distance, reduce braking performance, and create a potential risk of a crash, especially during emergency braking situations. The problem has been confirmed through diagnosis showing the c1391 trouble code. The issue has been identified as a brake system malfunction requiring repair of the brake booster/actuator assembly. The vehicle has been inspected/diagnosed by a service professional. The vehicle has not been inspected by police or insurance representatives. Toyota/dealer inspection information is available if requested. I contacted Toyota regarding the issue, but they declined assistance because the extended warranty coverage expired approximately 7 months prior to the failure. Before the failure, the vehicle operated normally. The first symptoms occurred when multiple warning lights appeared while driving, including the abs warning light, brake warning light, parking brake warning light (even though the parking brake was not engaged), and the traction control/slippery road warning light. These warning lights appeared suddenly, indicating a problem with the braking system.

I am the first owner of a Toyota 2013 Prius that I purchased in baltimore, MD, in 2013. I moved georgia in 2014. The car currently has 130000 miles. I heard there were recalls on this vehicle type few years ago, but I was never notified. The brake has failed recently with code c1391. I spent $3,500 recently and the car is still in the repair shop.

My 2012 Toyota Prius is experiencing brake actuator pump failure, presenting diagnostic trouble codes c1253 (brake actuator pump motor stuck/locked) and c1256 (brake actuator pump motor overcurrent). These codes trigger abs, brake, and vsc warning lights and disable abs and stability control. Toyota previously acknowledged this exact defect under customer support program zjb, which covered 2010-2015 Prius vehicles for brake booster and brake booster pump assembly failures triggered by these specific codes. I am the original owner of this vehicle, purchased new in 2012. I never received notification of csp zjb despite being the registered owner at the time notifications were distributed in 2019-2021. My current mileage is under 150,000 miles, within the secondary coverage mileage limit established by the program. Toyota has declined to provide goodwill coverage citing program expiration. This is a known safety defect that reduces braking effectiveness and disables abs — it should have been addressed through a mandatory recall rather than a voluntary program with an expiration date that left original owners without recourse due to failed notification.

On June 20, 2026 while driving the Toyota Prius I experienced a sudden brake failure. Initially I thought I might have pressed the accelerator instead of the brake. But then pressing the brake I found the car did not stop and the abs brake, brake lights, and other lights lit up on the dash board. The car had only 61,150 on the odometer. I called on Toyota for their warranty coverage but they declined saying that the vehicle is no longer covered. This brake failure should have been under recall. Aaa auto service has pulled c1391 vehicle code - requiring removing and replacing brake booster pump assembly with master cylinder, etc.

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.

The power brake unit and actuator are failing.

The contact owns a 2015 Toyota Prius. The contact stated that while driving at 45 mph, the brake warning lights illuminated. The brakes were inoperable and entered manual mode. The contact stated that the brake warning lights were red and yellow. The vehicle was taken to brake masters, where it was diagnosed with brake actuator failure. The local dealer was contacted but did not provide assistance. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 121,000.