general problems of the 2012 Toyota Prius - part 1

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 because a failing brake system is a critical safety hazard, and this issue appears widespread.

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 represents a critical safety defect, as sudden loss of braking assist while driving poses a significant risk to vehicle occupants and other road users. I am reporting this incident to document the hazard and request investigation into the reliability and safety of the brake system design. I am requesting you to please issue a recall and reimburse me , as these parts are very expensive , it affected my financial situation, thanks.

While driving 65 mph on the expressway on January 12th, 2026 under cruise control, I tapped my brakes to slow down. My brake warning light came on, along with the abs warning light, and the anti-swerve warning light. Cruise control no longer worked, and my brakes were noticeably hard to apply. I immediately had the vehicle computer checked and the issue is a leaking brake booster component, a faulty part known by Toyota to fail prematurely with this and other Prius models. No recall was issued however. The car is now unsafe to drive until a ~$4000 repair is done, according to my service representative.

The contact owns a 2012 Toyota Prius. The contact stated while driving at an undisclosed speed, several unknown warning lights illuminated, with an abnormal sound coming from the vehicle. The vehicle was taken to the dealer where it was diagnosed with brake booster failure. The contact was informed that the brake booster pump needed to be replaced. The vehicle was not repaired. The contact stated that the failure was a known failure with the vehicle. The manufacturer was made aware of the failure. The contact was informed that an undisclosed extended warranty program had expired. In addition, the contact was informed that the repair was not covered. The failure mileage was approximately 175,000.

Brakes went soft with little braking power. Traced the fault code to a faulty braking actuator; Toyota says this is past the coverage date for the recall.

While driving, the vehicle experienced a sudden brake system malfunction without prior warning or gradual degradation. The vehicle was being operated under normal driving, road, and weather conditions. No recent brake service, repairs, or aftermarket modifications had been performed prior to the failure. Multiple warning lights illuminated on the dashboard, including the abs warning light, brake warning light, and traction control warning light. Shortly after the warning lights appeared, the vehicle began emitting continuous warning beeps. Audible buzzing or pumping noises were also present from the brake system during the malfunction. During this event, brake performance was reduced and braking felt inconsistent. The brake pedal became hard at times and spongy at other times, requiring increased effort to slow the vehicle and resulting in unpredictable braking response. This created a safety concern while the vehicle was in motion. The driver was forced to alter driving behavior and exercise extreme caution due to reduced braking confidence and unpredictable pedal feel. The malfunction has occurred intermittently during normal driving. The condition temporarily resolves on its own and later reoccurs without corrective action. The suspected failed component is the brake actuator / abs actuator assembly. A diagnostic scan retrieved fault codes c1252 (brake booster pump motor on time abnormally long), c1253 (pump motor relay malfunction), and c1256 (accumulator low pressure), which are consistent with brake actuator malfunction. The failure occurred at approximately 154,000 miles. This vehicle model and generation have a documented history of premature brake actuator failures with similar safety-related symptoms reported by other owners. The condition places the driver and others at risk due to unpredictable braking behavior, reduced braking effectiveness, and repeated warning alarms while driving. Warning lamps and audible alerts continue intermittently.

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 Prius’s due to a faulty manufactured part. Codes were c1391, wc1256, and c1252. I believe this part should be recalled and Toyota should fix these faulty parts, especially considering they inspected my car and did not mention it as an issue despite it being a known issue. I got a second opinion from mavis tires and they concurred with the diagnosis but could not fix it.

The power assist braking system failed while I was driving in the rain. I was approaching a stoplight and I had to push down a lot harder and farther than I typically have to in order to stop. Luckily I was not going that fast and there were no cars ahead of me, but I stopped beyond where I had intended at a busy intersection. No warning lamps or messages had been illuminated prior to this happening. After the failure, the brake system, abs, and slip indicator lights were on and remained on when the car was restarted. An independent service center used a scan tool and found code c1391 stored in memory, indicating that the brake booster is unable to hold pressure due to an internal leak. The vehicle has not yet been inspected by the manufacturer, police or insurance, but can be available upon request.

I bought this car over a week ago for a good price, performed fine until I’m driving it home on the interstate and some abs/brake lights came on the dash. I enter my city and notice the brakes aren’t performing as tight as they were during the test drive. A few days later I take it to a local dealership to get it looked at. The brake actuator and pump had gone bad, causing this issue. It cost almost $5,000 to fix there, I couldn’t afford it so I had to only pay the $185 for the diagnostic. It’s an on and off thing, sometimes the lights go away and it brakes as it should, but most of the time the lights are on and the brakes don’t work as they should. I fear one day the brakes may eventually give out on me and cause an accident. I am available for inspection.

While driving 60 mph in highway, abs, traction control and brake lights lit up and vehicle lost its effective braking power. There were no prior warnings prior to this failure. It was a sudden incident. Since it wasn't rush hour, I could safely reduce speed and bring the car to stop. Situation could have been much different if it was normal hours. After taking the car to dealership, it indicated dtc code 1391, brake assembly failure. The car was fixed at dealership at cost of $3,000. When researched further, it appeared that there is broader pattern of failures. Numerous reports have been made by owners of 2010–2015 Toyota Prius, Prius phv, 2012–2015 Prius v, 2012–2014 camry hybrid, and 2013–2015 avalon hybrid vehicles, all of which share the same brake booster pump assembly design manufactured by advics CO. , ltd. Dealerships, including capistrano Toyota and claremont Toyota in California, have previously petitioned NHTSA regarding this very defect. Their 2019 letter to the agency documented that Toyota: * knowingly excluded hundreds of thousands of hybrids from prior safety recalls (doh 13v-235 and kol 19v-544) despite identical failures. *issued “post-failure” repair programs (warranty enhancements zjb, zkk, zkc, zlm, 20le03, 23te06 and 23te07) only after owners experienced brake failure. * identified the same dtc codes (c1252, c1253, c1256, c1391, u0293) in both recalled and unrecalled vehicles—codes that correspond to accumulator leaks, loss of brake pressure, and failure of brake assist and stability control systems. * admitted through technical service bulletin TSB-0130-19 that these defects caused loss of hydraulic pressure, increased stopping distance, and total loss of brake assist in affected hybrids. In short, the defect pattern across multiple hybrid models is identical to those already recognized by Toyota and NHTSA under prior recall campaigns, but for reasons unexplained, Toyota limited the recall population and left many consumers unprotected.

Traction control. Abs and brake warning lights all came on.

2012 Toyota Prius. The brake system malfunctioned and my daughter was almost in a wreck. The abs, traction control, and brake warning lights on the bashboard all illuminated at the same time. The brake pedal feels soft and is less responsive requiring more effort to stop the vehicle. The brake actuator assembly is making a hissing noise. Ran a abs test using a scan tool and received a c1391 error code. The code points to a leak within the brake actuator system. Upon research I have found that this is a very common and costly repair that Toyota has known about for many years. Toyota issued a customer support program related to this issue that ran for 10 years or 150,000 miles from the vehicle's date of first use. This car, being a 2012, is beyond the support program. I contacted Toyota, hoping they would do the right thing and cover the repair. I was told that they would not cover the repair or supply the parts to cover the repair. I told the rep. For Toyota that I did not feel like it was fair for Toyota to continue to put millions of drivers at risk for a product that they clearly realize for years now is defective and could hurt or kill someone. The code and the braking issue did not appear until after the customer support program ended and therefore we had no warning or way to anticipate this braking issue or the danger to my daughter and anyone else riding with her in the car or on the roadway near her travel routes. I traveled 300 miles, rented a uhaul car tow trailer and brought the car back home. My mechanic confirmed the code c1391 and the fact that the brake actuator has failed. The mechanic has ordered the parts (the same defective parts) to replace the broken ones. Toyota is still selling the same part as a replacement part clearly knowing that it is not safe and no warning came with the replacement part explaining the potential for a braking issue. Based on internet research this same part is in many 2005 to 2013 Toyota and Lexus.

I have a Prius v 2012, and the lights for abs turned on and when I checked on internet Toyota was repairing the part for 150k miles and 10 years but this is a safety feature my car is now at 149922, and while I was on road suddenly the signs came up and I the brakes were hard, and this is a problem for my safety and for others too since it doesn’t brake well.

After 13 years and 112,000 the brake booster and brake booster pump went out on my car. Toyota extended the warranty to 10 years because of this issue. Now just outside of the 10 yr mark my car has this issue and Toyota will not cover it. This is a huge expense and also a major issue with this year and model of car.

While driving on a city road below the speed limit, braking was compromised leading to loss of traction and failure of the abs system. During the incident, the brake, abs, and engine warning lights all turned on and a collision was only avoided due to pumping of the brakes. Further investigation by a mechanic revealed a failure of the brake actuator system. Failure of this system has increased the stopping distance of the vehicle considerably and makes braking unreliable and unpredictable.

I own a 2012 Toyota Prius c with approximately 156,578 miles. The vehicle has been diagnosed with c1391 – abnormal leak in accumulator, which causes the brake actuator to lose hydraulic pressure. This results in frequent buzzing from the actuator pump, illuminated warning lights (brake, abs, traction control), and loss of abs and stability control. The condition increases stopping distance and creates a serious safety hazard. Toyota previously acknowledged this exact defect under customer support program csp 21te01, which covered brake booster and pump assemblies for certain Prius and Prius c models when codes such as c1391 were present. However, the program expired on November 30, 2022, and my vehicle is just over the 150,000-mile coverage limit. Despite this, my Prius exhibits the same defect that Toyota has already recognized as a safety-related issue. Toyota carlsbad confirmed the diagnosis and quoted $3,399. 55 plus tax for repair, with a reduced courtesy estimate of $2,817. 86 plus tax, but declined goodwill assistance since csp 21te01 expired. Given the widespread reports of brake actuator failures in Prius models, I believe this represents a systemic safety issue that warrants NHTSA investigation and potential recall/extended coverage.

Brake getting stuck on the floor would have to press on brake really hard just to get a response, this will happen out of the blue! driving in highway or just driving off the driveway. I almost hit a car in front of me due to lack of brake, I had to swerve to the side! first appear 1 day after buying the car. . This issue needs to be worked on right away.

While driving on the freeway I applied the brakes and the brakes suddenly felt soft and not very responsive. At that moment 3 dashboard lights turned abs, brake, and the slip indicator lights. I carefully got out of the freeway, parked the car, and had the car towed to an independent mechanic. The mechanic detected brake booster and actuator problems, code c1391.

Brake actuator and abs accumalator failed. It is a common failure reported by multiple owners on these cars. I was on the high way going 70 when it failed and lost any brake boost I had putting me in a very dangerous situation where I narrowly avoided an accident. Upon scanning the car's codes I got code c1391 which I looked up and saw a bunch of other people who were also struggling with this issue.

While driving on the interstate I went to slow down to merge and my brakes failed. The following warning lights came master warning light (yellow), brake system warning light, brake system warning light (red), abs warning light, and the slip indicator light. My vehicle was towed to a Toyota dealership and after running a diagnostic test, they confirmed that it was the "break booster with accumulator c1391 stored internal leak of accumulator and need immediate attention" which they quoted at $4,295. 68 to fix. After researching the issue saw a customer support program 20te07 was issued taking responsibility for the faulty brake booster pump assembly however only covered the repair for a two-year period and only if it was one of the identified diagnostic trouble codes listed in the csp issued by Toyota but expired in Feb 2022. The code pulled from my vehicle 3 days ago was listed in this document, but the coverage only covers until Feb 2022. This is not a normal wear and tear issue, it is a faulty part that Toyota identified as a life and death safety concern but refuses to do anything about because mine didn't show an issue within their 2-year csp timeframe. Toyota identified that there are roughly 118,950 2012-2014 model year Prius v with a production period of late September 2010 to mid-November 2014 vehicles that this faulty part affects along with everyone else on the road with these vehicles as it causes failure of the brake booster pump assembly, which leads to a loss of braking assist and the deactivation of the vehicle stability control system. For the safety and lives of the owners of these vehicles and all of the other lives of the drivers on the road that this could affect in the case of this faulty part should there be a catastrophic accident, like mine could have been, a nationwide recall on this part must be issued.

While pulling out of a parallel parking spot going slightly uphill, I braked as I looked around the back of a double parked truck. I saw a car coming, braked hard, and suddenly my car surged forward across the street and hit a parked car. I looked down and saw that my foot was squarely on the brake pedal pressing down as hard as I could. The parked car was unoccupied, and I was uninjured. There were no warning lamps, messages, or other symptoms of the problem. I turned my car into the dealer for repairs and a fix to the sudden unexpected acceleration. They could offer no fix until a Toyota representative examined the car. On August 14, by an emailed letter, Toyota claimed it found no defects and it must be the result of driver error, specifically, my mistakenly hitting the accelerator. This is gaslighting denialism. (a) the edr data sent to me does not indicate that I hit the accelerator unless that data is in the page of hexadecimal numbers. (b) Toyota's claim that I hit the breaks at "-0. 2 seconds prior to the collision" is physically impossible. No one can move their foot from the accelerator to the brake that fast. (c) Toyota's claim is contrary to what I experienced and observed.

C1391 - abnormal leak in accumulator.

While driving my 2012 Toyota Prius, the traction control, brake, and abs warning lights all came on at the same time. I used a home obd scanner but it didn’t show any diagnostic codes. After some research and inspection, I discovered that the issue was related to a faulty brake booster and accumulator—something I’ve learned is a common problem with this model. I was relieved to hear that Toyota has an extended warranty on these parts. However, last night while driving, the brakes suddenly stopped functioning properly. It became very difficult to slow down, which put me in a dangerous situation. I’m deeply concerned about the safety risks this defect poses and believe this issue deserves further attention.

The brake booster and brake booster pump assemblies had to be replaced at the dealership. Parts are not available for inspection as far as I know. We were warned by the dealership that we should not be driving the car because the brakes could completely fail at any moment if we didn't have parts replaced. That would have been dangerous for us and anyone else sharing the road with us. On a Sunday, leaving our house and driving down our street, three lights turned on on the dashboard display - traction, brakes, and abs - and the brakes felt softer and less responsive than normal. After having gotten a diagnosis and repair estimate from the dealership, we carefully drove the car home to consider our options. We tried to get a second opinion from a trusted mechanic, but it sounded like the parts we needed were tightly monitored by Toyota and the original estimate for the repair from the dealership was above $3,000. After a few days, the dashboard warning lights turned off and the brakes felt back to normal. The whirring noise which had been happening roughly every 4 seconds had slowed to roughly every 10-12 seconds. We were told that this turning off of the lights sometimes happened, but that the issue was still the same. Prior to these lights turning on, the car had been making a lot of the whirring noises for some time, but it had never thrown the codes before that would have been picked up by a mechanic. At the time, we didn't recognize the sounds as a sign of an impending commonly recognized failure - only after doing some research did we find that this was a very common problem for a lot of Prius owners, especially for the given year and number of miles we had. There is an "extended warranty" for this part and repair, but while we were within the mileage limit, we were outside of the time limit and we were told at the dealership that Toyota would be inflexible about paying for the repairs.

I am reporting a sudden and dangerous failure of the brake booster in my 2012 Toyota Prius. While driving, I experienced a loss of braking power, accompanied by several warning lights including abs, brake, and the traction control system. The brake pedal became extremely stiff and unresponsive, significantly increasing the stopping distance. This failure nearly caused an accident, as I was unable to stop quickly enough when traffic slowed unexpectedly. This issue happened without warning and is a serious safety risk. I later discovered this is a common and widely reported defect in 2010–2015 Toyota Prius models. Toyota issued an extended warranty (customer support program ze3) to cover this known brake booster defect — but only for vehicles within 10 years or 150,000 miles. While my Prius has well under 150,000 miles, it is just over 10 years old, which disqualifies me from coverage, leaving me with a repair estimate over $4,000 for a well-documented manufacturer defect. This seems grossly unfair, especially for responsible owners with low-mileage, well-maintained vehicles. Toyota’s refusal to issue a formal recall and instead offering only limited support puts millions of Prius drivers at risk. A brake system failure of this kind should qualify as a safety defect and trigger a mandatory recall, not a quietly limited program with arbitrary expiration dates. I urge NHTSA to investigate this issue further and consider a recall of the defective brake booster system in these Prius models to protect public safety and ensure fair treatment for affected owners. Thank you.

The contact owns a 2012 Toyota Prius v. The contact stated that while driving at an undisclosed speed, the service brakes warning light illuminated. The vehicle was taken to the dealer, who diagnosed failures with the brake booster assembly and brake booster pump assembly. The vehicle was not repaired. After investigating the failure, the contact related the failure to customer satisfaction program: 21te01. The manufacturer was notified of the failure and referred the contact to the NHTSA hotline for assistance. The failure mileage was unknown.

The contact owns a 2012 Toyota Prius. The contact stated while driving 30 mph, the abs and traction control warning lights illuminated. The contact stated that while attempting to depress the brake pedal, the vehicle hesitated while responding. The contact stated that there was a buzzing sound coming from accumulator pump. The dealer was contacted. The contact stated that the failure had occurred on several occasions. The vehicle was taken to nico's auto repair where it was diagnosed and determined that the brake booster and accumulator assembly needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure but offered no assistance. The approximate failure mileage was 140,000.

I am writing to express a complaint regarding the issues I have experienced with the brake system of my Toyota Prius c, 2012 model. For the past several months, I have noticed that the brakes exhibit strange noises, soft pedal sensation, reduced braking efficiency, were driving and the abs, traction, brake, and that other light turned on and the brakes became slow these issues have been observed on multiple occasions and pose a safety risk to myself, other drivers, and pedestrians. I have taken the vehicle for inspection, but the problems persist or have not been definitively resolved. I believe these faults may be related to defects in the braking system, and therefore I request a thorough inspection and necessary repairs at no cost, considering that the manufacturer could be responsible for manufacturing defects.

This Prius hybrid is my [xxx] mother's car which she got thinking is was a very safe and reliable vehicle. She purchased the vehicle from a Toyota dealership here in maine on [xxx]. Last week while driving down the road, all of a sudden, every brake warning light lit up the dashboard and the brakes became extremely unresponsive. It scared us both to death but thank goodness, I was driving when this happened. After doing some research, I have discovered that this a very well known brake issue with the 2010-2015 Prius cars. I cannot for the life of me understand how this major safety defect has not been made into an actual safety recall. I did contact Toyota customer service and they will not help us at all. Even though my mother has only had the car for just under 9 years and is well under the allotted mileage, they said their customer support program (zjb) only covers 10 years from the day the car was first driven after production. Her Prius now is inoperable and the repair costs are in the thousands. We are so incredibly disappointed with Toyota and the safety board for allowing this to happen to all of the defective Prius owners. I hope you will reconsider and do the right thing and recall these cars before someone does get into an accident where they are injured or killed. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

My brakes began making a funny noise when I used them. I only have 80000 on the car and do regular maintenance. I took it in because it seemed the brake pedal was getting spongy as well. They ran in through diagnostic tests and determined the braking module or brake booster/master assembly was bad. This seems to be an issues with Toyota and should be addressed immediately. It is an expensive fix for a low mileage car.

47050-47180 47070-47060 both failed at same time along with many others getting quotes of 3500-4000 to replace no brake control or anti lock brakes.

Brake booster failures are a common safety issue with 2012-2015 Toyota Prius' this one included is starting to fail which can lead to abs deactivating and shorter braking distances. There was a recall for this part but most tend to fail after the warranty period. Leaving many vehicles unrepaired and dangerous.

Brake system went out suddenly making the car brakes not work.