Automatic Emergency Braking Problems of Toyota Prius - part 1

The brake actuator and compressor is having repeated problems and causing the brakes to lock up completely while driving both in city and on the highway. Abs/parking/normal brakes the lights on the dash all start flashing and beeping. Abs / emergency brake / exclamation warning / sliding / lights all on it also caused the speedometer to stop working and most of the lights of the computer part of my dash to not display information problem code 1391 confirmed by mechanic this is a danger to me and other drivers and Toyota needs to take responsibility for these repairs because it can cost us our lives.

See all problems of the 2013 Toyota Prius 🔎.

Upon a hard (but not emergency) brake, my abs and brake warning lights came on and my car began whirring once every few seconds. I immediately took the car to the Toyota dealership, who informed me that my master brake cylinder and booster had to be replaced, and that issues with the booster were something they had seen frequently in this generation of Priuses. I paid $5095 for repairs and inspection, but I had no other choice, as my brakes could have gone out at any moment whilst I was on the road and caused a very serious accident.

The brake actuator/abs hydraulic system on my 2013 Toyota Prius failed. The component is available for inspection upon request, as it was replaced by a Toyota dealership. Prior to failure, the vehicle intermittently displayed abs, traction control, and vsc warning lights while driving, which would sometimes clear on their own but eventually became persistent. This condition reduced or disabled abs, traction control, and vehicle stability functions, increasing the risk of loss of control or reduced braking effectiveness, particularly in emergency braking or low-traction conditions. The problem was reproduced and confirmed by a Toyota dealer, who diagnosed the failure using diagnostic code c1391 indicating internal brake actuator malfunction. The vehicle was inspected by the manufacturer’s authorized dealer, who replaced the brake actuator assembly after three days of repair at a cost of approximately $3,000. Warning lamps were present for months prior to the final repair and gradually progressed from intermittent to constant, indicating a worsening failure of a known issue affecting this generation of Prius vehicles.

The abs failed while driving on the highway. There was no accident, but it was substantially harder to brake when needed.

See all problems of the 2015 Toyota Prius 🔎.

While driving, my brakes became mushy and ineffective. Brake warning lights came on, also. It was very scary driving in rush hour traffic with little to no brakes. There was no reliability. Just keeping as much as possible space between cars, using hazard lights &prayer.

The brake system malfunctioned suddenly. While driving and while stopped, the brake pedal became very hard and braking behavior became unpredictable. The vehicle sometimes brakes aggressively and other times requires excessive pedal force to stop. The abs and brake warning lights illuminated. The vehicle no longer provides normal braking assistance. This issue is related to a failure of the brake actuator / brake booster, which is a known issue affecting Toyota Prius models from 2010 to 2015. This defect creates a serious safety risk, as braking performance is inconsistent and may increase stopping distance or cause loss of control during emergency braking situations. The vehicle has not been repaired yet because the cost is very high and the manufacturer has declined assistance despite this being a known safety-related defect.

See all problems of the 2014 Toyota Prius 🔎.

On [xxx], we were driving from coalinga, CA to phoenix, az for thanksgiving. As we began to descend into los angeles on [xxx], three warning indicators suddenly went the abs warning light, the traction control light and the brake warning light. The brakes still worked but the brake assist was weakened. We pulled over as soon as possible at the nearest autozone. The employee performed a standard handheld obd-ii scan of the vehicle and did not detect any issues. We continued on our way through los angeles and to san bernadino where we were spending the night. At one point the indicator lights went off for a few minutes but then came back on. We spent the night in san bernadino, and the next day (11/26/2025), we took the car into the san bernadino Toyota dealership as we felt it was unsafe to keep driving. The dealer conducted a thorough full brake and hybrid system diagnostic and confirmed that the failure was inside the brake booster system. The repair estimate states: "brake booster assembly with master cylinder and brake booster pump assembly have an internal leak. " thus, Toyota's own technician identified an internal hydraulic leak within the booster system, affecting the booster assembly, master cylinder, and booster pump assembly. The total repair estimate is $3,959. 99. This is a major safety defect affecting sealed hydraulic components that are not part of routine wear-and-tear. There were 4 people in the car. Fortunately, the brake failure did not result in an accident, but it could have if we had kept driving on to our destination. We contacted the Toyota brand engagement center to ask for goodwill assistance, but they were unable to help us. In addition to the repair costs, we have incurred rental car costs. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

Brake actuator failure requires actuator and master cylinder replacement. All dash lights came on while driving. The vehicle was diagnosed at brian easler Toyota in hendersonville north carolina. The brakes are still operational temporarily but spongy and expected to fail so the car is not drivable. I expect to have the actuator and master cylinder replaced in then next few weeks at a cost of $5600. I see there were previous recalls on the braking system that have now expired.

The brakes suddenly failed in our 2013 Prius v while she was driving with our two young children. It was extremely scary, and very dangerous. Toyota has known about the braking system issues for years but refused to offer a recall to avoid costs. This needs to be immediately addressed.

2025 Toyota Prius xle. The upgraded 12 inch infotainment flickers light then dark then back to light several times. Automatic braking is being turned off without knowledge. The Toyota cruise control and adaptive cruise control will say unavailable or see owners manual. Different safety features will turn off on their own. The 12 inch infotainment center will switch from apple car play to regular radio (sirius xm) on its own.

See all problems of the 2025 Toyota Prius 🔎.

The abs system and the brake actuator began to fail, which triggered multiple warning lights. The Toyota dealership service department confirmed that the anti-lock brake system and the actuator needed to be replaced, a $3800 value.

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.

See all problems of the 2012 Toyota Prius 🔎.

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.

In June 2025, while driving on the highway, the vehicle suddenly displayed multiple brake warning lights and warning messages, including the red brake warning light, abs light, brake system warning light, and traction/slip indicator. At the same time, the brake pedal became stiff and braking effort increased suddenly, creating a near-crash situation because the vehicle did not slow normally. Before that incident, the vehicle had already been making abnormal brake-related noises, including a humming/pumping noise when the brake pedal was applied, and there were intermittent episodes where braking felt abnormal. In June 2025, the vehicle was taken to a Toyota dealership during Toyota’s brake booster support program period. The dealership documented customer complaints of “humming noise in cabin when holding foot on the brakes,” a request to “scan for codes for zjb enhancement,” and that the “vehicle hard to accelerate and brakes got stiff,” but stated that no qualifying abs codes were present at that time. In March 2026, the same condition returned and worsened. The vehicle again displayed the red brake warning light, abs light, brake system warning light, and traction/slip light, and braking performance was reduced. An obd scan of the abs control unit showed code c1391, which is associated with brake booster / abs actuator failure. The Toyota dealership has now diagnosed the vehicle with abs actuator and brake booster failure and quoted repair. This is a serious safety issue because braking became more difficult while driving, including on the highway, with sudden warning lights and degraded stopping ability. The failed components are available for inspection. The problem has now been confirmed by a Toyota dealership. The issue was reported to a Toyota dealership during the prior support-program period but was not confirmed then.

I have have 2 problems, both was recalls, but this one they say expired in 2021 when I bought the car and Toyota dealer didnt tell me had recall so I could fix it before it expired. There is a class action lawsuit in the brake booster, master cyclinder actuator abs pump fialing loosing brakes making grrr noises leaking all brake fluid out continously dangerous to drive can cause bad accident wreck since I drive down the hwy alot and this is the only car I have to drive, I also have DC inverter module /sensor that is killing off 3 batteries now that I installed in 3 months, and Toyota dealers wont fix unless it shows error but its a recall so since problen should fix this recall but wont pay for it to fix it even though it a recall right now that is not expired. Im upset 3 dealers wont do it unless then charge me to do it. When Toyotal mfg take it to any dealer and they will fix free but no one will do it. Toyota mfg needs to make these dealers fix these 2 recalls on this car that can kill me and my passengers and anyone on the road that I could hit by not haivng controll brakes or the hybrid system shuttong completely down and could even kill a pedestrian with these 2 recalls that dealers wont fix but mfg said they need to everyone with these cars I see are having these same problems. Need make the Toyota mfg and dealers fix these free of charge before more people get killed injuried or cause more accidents ,.

See all problems of the 2010 Toyota Prius 🔎.

Vehicle warning lights for brakes, abs and traction control all on while driving. Per mechanic, known problem on Prius and repair cost is $3-$5k. Covered by a prior customer support program but has expired. I have two Prius’s with the identical problem - bill will be up to $10k error codes c1391, c1214.

Vehicle warning lights for brakes, abs and traction control all on while driving. Per mechanic, known problem on Prius and repair cost is $3-$5k. Covered by a prior customer support program but has expired. I have two Prius’s with the identical problem - bill will be up to $10k. Error code c1391.

Our trac abs and brake lights came on and braking became more difficult but not totally gone. I took it to my mechanic (not Toyota dealer) and he said the codes were going off for the abs hydraulic system and it would be $3000 to fix! this is unacceptable. I feel like my safety is affected but no one else has been hurt yet. I’m trying to be proactive. They first appeared last month. No manufacturer, insurance agent or cop has inspected it. It can be inspected by appt. Please help.

See all problems of the 2011 Toyota Prius 🔎.

On 10-17-24 these warning lights came 1. Pre-collision system 2. Hybrid system 3. Airbag 4. Safety connect red light and intermittently: 1. Slip indicator 2. Brake system cruise control would not set, and displayed "e3". ------- component failed: dealer determined that the driver's side door harness had been chewed by a rat that had entered the under dash area "somehow". They said it couldn't be repaired but must be replaced. My insurance deductible was $500 and they paid the balance of the $1,387. 06 bill. (I have retained the harness, which could have been repaired by splicing the two wires connecting to the driver's side airbag collision sensor. The labor to splice the wires would have been less than an hour. ) ------ safety: the chewed wire apparently disabled the airbag, pre collision, emergency automatic braking, seatbelt pre-tensioning, abs, and stability systems. ----- the dealer confirmed the problem. ----- my insurance adjuster did inspect the harness. ----- I placed electronic rat traps in the vehicle, which killed three rats. ========= next ========= all the same warning lights came on a few months later! I didn't throw more money at the dealer, and took off the panels to inspect the wiring myself. There was damage to the passenger side door harness wires. I removed the harness and ordered a $60 used replacement on ebay. While waiting for delivery, I researched rat damage to Toyota wires, and how rats could possibly enter the interior of the car. I discovered that there is an unscreened 12x9 inch opening to bring fresh air into the hvac system. It is hidden under the windshield wiper cowls. Also, there are two unscreened vents in the trunk area. Other Prius owners covered those openings with 1/4 inch metal wire hardware cloth. I spent a few hours disassembling, covering, and reassembling pieces to prevent further access through the fresh air intake, and will do to the rear next. Toyota should recall these cars and ratproof the harnesses.

While driving through the mountains, the abs, brake, and slippery (traction control) warning lights all suddenly illuminated on the dashboard. This happened without any noticeable trigger, and the warning lights remained on for the duration of the drive. I'm concerned about potential issues with the braking or stability systems and request a diagnostic check to ensure everything is functioning properly. Also I am aware that there was recall on Prius 2010 related to abs system. My VIN was not included in that but seems like similar issue.

The brake booster assembly (part number 47070-47060) on my 2013 Toyota Prius has failed. This component is critical to the proper functioning of the braking system. It is currently still installed in the vehicle and available for inspection upon request. As a result of the failure, the abs warning light, traction control light, and brake warning light are all illuminated on the dashboard. The braking performance has noticeably declined — the pedal feels inconsistent and at times unresponsive. This has created a significant safety risk while driving, especially during sudden stops or in wet conditions, as it compromises the vehicle's ability to brake efficiently and predictably. The issue has been confirmed by a Toyota dealer (or independent mechanic if that’s the case — feel free to change this line accordingly). The dealer diagnosed the issue as a failure of the brake booster assembly, which aligns with known failures reported by many other 3rd-generation Prius owners. The vehicle has not been involved in an accident, and has not been inspected by the police or insurance representatives. Toyota previously issued a customer support program (csp zjb or zg1) covering this part, but it has since expired. I only recently began experiencing symptoms and was unaware of the csp until after contacting Toyota. Prior to the warning lights, I experienced intermittent symptoms such as a soft or delayed brake pedal, and an unusual sound from the brake system when the vehicle was turned off. The warning lights first appeared around [insert approximate mileage or date here], and have remained illuminated since then. Given the safety-critical nature of this component and the known defect history, I am requesting assistance from Toyota in the form of goodwill coverage or reimbursement, and would like this issue escalated for further review.

My abs system light is on. The Toyota mechanic has determined that it is due to nitrogen gas from a component of the brake booster pump assembly could leak into the brake fluid. As nitrogen is released into the brake fluid, the brake pedal may have reduced hydraulic pressure. Under certain circumstances, this condition could affect stopping distance and increase the risk of a crash. Toyota recalled model year 2010 Prius vehicles manufactured March 31, 2009, through October 9, 2009. I took my Prius to Toyota to fix this abs recall problems but they are refusing to fix the problem for free. They are charging me $4000 to fix it.

As I was pulling my car into a parking space with the brake applied lightly, the car suddenly lost braking and lurched forward when the front wheels touched the curb. This caused the front of the car to jump the curb and hit a tree a foot or two away. My foot was on the brake during this and the car did not brake automatically, or engage any other sort of safety measure. This was terrifying and I could have easily hit a pedestrian or injured myself and the passengers of my vehicle on impact. I completely lost control of the vehicle's braking due to this issue. Since the incident happened today, my vehicle has not yet been inspected. No warning lamps of any kind had been activated. The car was nearly brand new. Upon further investigation, there are numerous reports of similar events happening to Toyota hybrids over the years. A simple google search for this turns up many reports. These reports center around sudden loss of braking from the regenerative braking system and a "lag" before conventional braking is applied that causes the forward lurch due to the momentum of the car. Many others on online forums seem to also suggest running into this issue specifically when the wheels hit a bump. This sounds exactly like what happened to my car, causing it to lose control despite my having the brake applied. It is insane that such a problem has existed for years in the braking system without being fixed by Toyota.

Failed brake booster and pump assembly, confirmed by Toyota service. Warning lights turned on all at once: aeb, skid control and brake light. Estimated cost to repair is $3,000.

I am writing to express my concern regarding an issue with the pcs system dash lights on my 2010 Toyota Prius. I recently became aware of problems related to the brake booster system, which I understand have been addressed through recalls or warranty extensions on certain models. I believe that the issue I am experiencing should be covered under warranty, and I kindly request your assistance in resolving this matter.

Brake warning came on and wouldn’t go off. Followed by continuous beeping and now the brakes are no longer working properly. You have to force the brake all the way to the ground to even come to a rolling stop. The problem first occurred on 3/8/25. The brake actuator seems to be a reoccurring problem that Toyota addressed but is no longer fixing. It is dangerous to drive my vehicle and others have said their brakes have completely failed when this problem arose.

Breaking system failure do to asb actuator, breaks are locking and vehicle is engine braking.

See all problems of the 2009 Toyota Prius 🔎.

Brake booster, brake accuater went out even after the recall. Dealership said they could do nothing to help.

My car is at 89k total miles and last week I had three warning lights pop up on my dash (traction control, brake, abs) which indicates something wrong with the automatic break system. My car is under 100k miles and I purchased it used in 2016, under ten years ago, and this problem is way too early to happen in my make an model. I got a code read on the issue (c1391) which indicates that my abs actuator is leaking/broken, a major safety issue as it happened as I was driving. Again, this should not be typical as I only drive a few miles per day on average.

Anti lock brake malfunction. Code c1391 leak in brake accumulator. This seems to be a common code for brake issues with Prius. The cost to repair is significant, more than the value of the car. This is a certain safety issue that needs to be addressed. This is clearly a hazzard and will cost lives to those who cannot afford the cost of repair.

Twice while I was driving on the highway, my abs and brake light came on, and my brakes became less sensitive to pressure. That is to say, it took more effort and I had to push my brakes further towards the floor in order for them to respond. I went to an independent mechanic and got the code c1391 which indicates a brake pump accumulator issue. I went to a Toyota dealership and and had the car inspected. They confirmed the c1391 code and said the brake booster assy with master cylinder pump assy was malfunctioning. However, I was never told by Toyota that this issue meant my brakes could fail at any time. My safety and the safety of others was put at risk because my brakes spontaneously became less responsive, my stopping distance was increased, and they were at risk of spontaneous failure.

The contact owns a 2018 Toyota Prius. The contact stated that while in bumper-to-bumper traffic, the vehicle suddenly accelerated. The brake pedal was applied but failed to respond. The driver crashed into the front passenger side of the Lexus. The vehicle continuously moved forward. The contact was eventually able to pull over safely. The pre-collision malfunction warning light illuminated. The brake malfunction light was flashing. The air bags did not deploy. There was no reported fire or injury. A police report was filed. The vehicle was taken to the local dealer, who could not determine the failure. The vehicle was not diagnosed or repaired. The vehicle was then towed to an autobody center where it remained. The manufacturer was contacted, but no additional assistance was provided. The approximate failure mileage was 39,000.

See all problems of the 2018 Toyota Prius 🔎.

Took car in for repair because all the warning lights are on. The repair shop quoted $1200 for anti lock braking actuator system which is defective. This is a huge safety issue and a costly repair from Toyota.

The engine light went on while driving on the highway. We immediately pulled over and had the vehicle towed to the nearest dealership. The dealership informed us that both the brake actuator (Toyota part to44500-47141) and water pump (Toyota par tog9020-47031) had failed. The car was no longer save to drive.

Nhtsa campaign 13v235000 Toyota will notify owners, and dealers will replace the affected brake booster pump assemblies. The recall is expected to begin late July 2013. Owners may contact Toyota at 1-800-331-4331. Toyota is no longer honoring this recall. They think it is acceptable for me to drive around with unsafe and defective brakes.