general problems of the 2015 Toyota Prius - part 2

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.

While driving my 2015 Toyota Prius, the brake pedal became extremely stiff and hard to press. I was on the way to the dog park with my dog in the back seat when I had to press down very hard just to slow the car at a traffic light. It felt like I was stepping on a rock. The brakes barely engaged, and I had to use far more force than normal to get the car to stop in time. When I hit the brakes, they finally caught hard and suddenly and my dog went flying off the back seat and landed on the floor. She’s fine physically, but now she’s terrified of getting in the car at all. It was scary for both of us and felt totally unsafe. If I had been going just a little faster or if someone was walking across that intersection, it could’ve ended badly. I later found out this issue is tied to a known defect with the brake booster and accumulator system, specifically related to code c1391. Toyota even acknowledged this problem in a customer support program (csp zjb/zkk), but they refuse to help because my car is slightly over the mileage limit. That doesn’t change the fact that this is a serious, dangerous failure that affects the driver’s ability to stop safely. Toyota should be forced to take responsibility for this failure before someone gets seriously hurt.

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.

Abs break actuator and abs pump failed while driving losing loss of breaking. Toyota is aware of this problem but refuse to fix this notorious and dangerous problem they have with multiple model years. I was not informed of the limited service campaign. This should be recalled as a safety to the public.

Brake failure during operation due to bad brake booster pump and accumulator.

Brake booster failed while driving down the mountains back from big bear. Nearly wrecked several times, had no idea why my brakes weren't working properly. Go to autozone to scam the code, and I got the dreaded abs failure. Sadly the extended warranty for this known issue from Toyota conveniently expired 2 weeks before the failure. Toyota should be held accountable and pay for my repair, that o did myself. Parts cost me $1800, plus a day off from work I had to take. Atrocious situation, Toyota should be ashamed.

Toyota hybrid brake problems 2015 Toyota Prius I took to my dealership jim ellis Toyota in mcdonough GA. I was told that my brake master cylinder & brake booster pumps vehicle has failed. I experienced my brakes locking up, causing the vehicle to unexpectedly lunge forward or failing to engage when the brake pedal is depressed. On [xxx] my abs, brake, traction lights came on out of nowhere. I tried taking it to my dealership in April to jim ellis, Toyota of mcdonough for the lights, the one lights being on. I took it there around 8 o’clock in the morning and then there was a very rude and disrespectful service person by the name of victoria who told me that they would not be able to see me and told me that I needed to leave because I didn’t I have an appointment. This is a dealership that I purchased this car phone in 2018 and I have been taking my car to jim ellis Toyota of mcdonough since 2018 to get regular oil changes and other maintenance for my car. Such as things my brakes replace my front and the back brakes have my battery please and come several times out of the year to get a oil change because I have part of what they consider a lifetime oil change on my car. Also, I had a warranty whole time that I have been taking my car to the dealership they never once brought to my attention that there was a known recall for the brakes booster. It wasn’t until I took my car to dealership on Friday 5/30/25 that I was advised that this was a known issue for 2010-2015 Toyota Prius jim ellis dealership knew about the problem and failed to make repairs when I spoke with general manager lorenzo smith he advised that past the recall timeframe and my warranty has expired. Jim ellis dealership knew their were known issues and hid the issue I refuse to write the wrong by making the repairs to my vehicle. They’re trying to charge me over $3200 in repairs when I spoke with the general manager, he advised me that they didn’t make the repairs because my vehicle VIN number. Information redacted pursuant to the freedom of infor.

I own a 2015 Toyota Prius, purchased new and put in service December 4th, 2014. Car is well maintained. On may 10th, 2025 the brake booster pump and assembly failed. Has internal leak. I had the dealer confirm this. Lights on the dash, computer code c1391 ( abnormal leak in accumulator, rec replacement of brake booster and pump) and brake booster pump is pumping every 3 seconds from internal leak. Brakes are now at 50%. Soft. The pads and shoes are perfectly fine. It’s the brake booster pump assembly. Toyota issued instead of a recall, which would have been the right thing to due considering its long history of these over multiple years failing, just a customer service letter. 10 years or 150,000 miles, which ever comes first. Mine failed at 10 1/2 years. Now I am stuck with a $3,000 bill which I can not afford, to replace the brake booster pump and assembly. Toyota completely knows of the issue and side stepped having to issue a recall on this very well know problem.

Left our house and as we were driving out of our neighborhood the abs and brake lights came on. We looked it up in our book and couldn't find anything concrete to go on. Drove straight to auto zone and their test came back most likely brake booster or master cylinder. While looking it up, we read several stories people had posted saying this was a defect with 2012 - 2015 Toyota Prius' and to write to you and tell of the incident. I put my VIN # in and it doesn't show any recalls about this. Any feedback would be helpful. Thank you!.

Car feels like it lunges forward while braking over bumps. I have learned this is a known manufacture defect with the brake booster and brake actuator which Toyota is refusing to replace outside of 10 years from manufacture date. This is a critical safety item and failure can result in loss of brake power. Most owners do not know this part even exists until failure has happened already.

I was driving down the road when I noticed my brakes were not working. I had to push a lot harder on the pedal to slow the car down luckily, I did not crash into the car in front of me. I pulled over to see numerous lights on the dash such as traction, abs, and brakes. I had the car towed to Toyota where they quoted me almost $3000 to fix the brake accumulator and booster assembly. They said my car is outside the extended warranty of this problem. My car is a 2015 Prius with 154k miles. I found online that these things fail commonly on this generation of Prius. It's horrible for this company to charge us basically the cost of the car to fix the brakes.

Brake booster and master cylinder failed. Traction control and abs lights came on while driving. Upon inspection there is an issue with the brake booster and master cylinder. This is an issue that Toyota is aware of and were repairing under a customer service campaign. They are aware that these parts malfunction and instead of recalling them, they set expiration dates for free replacement. The car must be experiencing an issue and throw the correct code within the campaign window to be eligible for complimentary repair. The brakes failing in this way could cause great harm to me as a driver and others on the road making it imperative that I pay thousands in repair cause to ensure everyone's safety, though that is Toyota's job.

Brake booster failed on 2/11/2025 its a known safety issue with Prius 2015 models. I took car to Toyota for repair. They told me it needs to be replaced but out of warranty as this cr was produced in oct 2014 this is a major safety item. I took it in for 100000 miles check and it was not replaced then and now they are saying it is too late.

The abs and traction light appeared on the dash while driving on the freeway. I attempted to brake, while merging to exit but the car brake system did not respond. Luckily there were no cars close to us. Figured it could be a brake fluid problem so I added more fluid and it went away for a bit. It’s come back again and my car feels unsafe to drive. The brake pedal feels stiff or sometimes mushy like dough. I am waiting to get a diagnosis on my car but from what I’ve read and what other Prius owners are reporting, it appears to be the “break actuator and break booster pump” that is failing to work properly. Wondering if any other Prius owners have filed a complaint.

The contact owns a 2015 Toyota Prius. The contact stated that while driving at an undisclosed speed, the abs and the traction control warning lights illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed with a leak in the brake fluid hose. The contact was unsure what repair was performed, but the vehicle was repaired. The contact stated that the failure reoccurred with an abnormal sound. The vehicle was taken back to the independent mechanic, and the contact was informed that the vehicle needed to be taken to the dealer for a complete diagnostic test. The vehicle was taken to the dealer, where it was diagnosed with brake booster failure. The contact was informed that the brake booster needed to be replaced. The vehicle was not repaired. The contact was notified of customer support campaign: zjb; however, the contact was informed that the repair was not covered under the customer support program because of the 10-year 100,000-mile limitation. The manufacturer was made aware of the failure, and a case was filed. In addition, the contact stated that the customer support program: zjb, was mailed out to customers 10 years ago. The contact stated that the information was never received. The failure mileage was approximately 114,000.

Brakes failing while driving in the rain. I was unable to use my brakes in the rain and headlights turned off while driving too. Took it to the dealer and they won't do anything unless lights are on on dashboard to read the code.

Bad break booster and was told I can’t get it repaired under the replacement program because it has to many miles! however I purchased my 2015 Prius used that had over 100 k already never received no notice from manufacturer or the dealer I bought the car from this is not fair and if Toyota is putting in faulty brake boosters, they should be replaced for free regardless of the mileage because I didn’t break the booster it’s the brake booster that was originally installed by the manufacturer! someone needs to do something, especially if it’s not the car owner‘s fault it’s the manufacturer fault for installing faulty parts! I need my car as a single mother I can’t afford $2000 for repairs and labor.

On the morning of December 11th, 2024, the brake system warning light (abs, yellow) illuminated on the dashboard along with the red brake indicator and the yellow vehicle stability control (vsc) system light. I consulted a mechanic who performed a computer diagnostic and informed me that the abs module booster had failed. He said that will order the part to change it but meanwhile he advised me to drive more cautiously and maintain a greater distance from the vehicle ahead, allowing extra space for my car to stop due to the increased braking distance caused by the failed abs module booster. Later that day, at approximately 5:30 pm, I was driving home in heavy traffic, with speeds not exceeding 40 miles per hour. The vehicle in front of me began to decelerate abruptly. When I applied firm pressure to the brake pedal to slow down my car, it lost all control. The vehicle began to skid, with the amplitude of the skid increasing progressively. It struck the highway guardrail on the left, changed trajectory, crossed all four lanes to the right uncontrollably, and ultimately collided with the highway guardrail on the right side.

There is a known brake booster issue with the Toyota Prius. They extended the coverage to 150,000 miles. My car is at 127,000 miles and they said the repair isn't under warranty and will cost over $3,000 to fix. There was no pre-warning lights or information received about this repair notice. I only noticed this when the lights came on and our abs lights went out. When I took it in they said I missed the deadline by 5 days, that I would have had to let them know by 11/20/2024. Which is insane for such a huge issue when I am well under the mileage coverage.

"abs actuator and brake pump - remove & replace - hydraulic booster assembly" -high voltage auto llc bakersfield, CA actually scared for my life when driving now. Brakes are now limp, constant sound of actuator cycling, code is c1391 problem is reproduced by dealer and independent service. Yes parts were inspect by manufacture. There are multiple warning lamps, actuator cycling is constant piror to lamps finally indicating issue.

Abs/ brakes, traction control warning lights came on 5 days ago. Dealer stated dtc 1391 code detected and recommend brake actuator replacement and brake booster assembly. Toyota issued TSB 0024-19 for service.

As many others have reported, the brake accumulator has failed. The symptoms began at 100,000 miles. When reported to the dealership, was brushed off as not a safety concern. It is, indeed, a major safety concern. My partner had the abs lights come on and brakes freeze up while driving on a fast and congested highway. Furthermore, getting this repaired is nearly impossible. The only Toyota dealership in town is estimated a $5k price. And since independent shops often cannot perform this repair, there is no comparison possible. They simply push to buy a new vehicle instead of standing by one that should be operating normally. The dealership is miracle Toyota of north augusta SC. Consistently does not support the consumers concerns and simply pushes repurchase as the only reasonable avenue. This is a known issue for Toyota that has stranded many of us without the ability to keep this car on the road. Please resolve with reasonable repair options due to faulty design.

Unknown brake issues.

The abs brake light on. The problem is related to booster pump assembly.

I started hearing the whirring sound from the brake booster that normally only comes on at startup almost constantly, about every 15 seconds. Along with this, a puffing sound and a pulsing from the brake pedal when stopped with the car on, such as at a traffic light. Also, when coming to a stop there would be a shudder from the brakes. After about a month I was driving when 3 separate warning lights lit up on the dashboard and the next time I braked the pedal felt very different than normal, very mushy, and the car seemed to not stop as well. I consulted a repair shop and they told me it’s a common problem with this model: brake booster/actuator failure resulting in a loss of the abs system. They quoted me over $2000 to make the repair. Internet research confirmed that this is a common problem that Toyota is aware of but refuses to acknowledge as something to be recalled, despite the huge safety risk associated with it. This on a car with only 85,000 miles.

Driving making slight turn car locked up steering wheel, brakes and gas all locked up ran in to a wall. The vehicle just failed with no prior warning.

My brake booster is failing and has been confirmed with certified Toyota master mechanics at Toyota dealerships that it is failing. Toyota has a csp called zjb to replace these once the brake booster fails. My car has been identified as one of the cars with a faulty brake booster and I’m terrified to continue to drive it as it has to throw a code and break before they will change the faulty part. I want them to fix it before it fails and someone gets hurt. What do I do? there are a lot of other complaints about this but Toyota is not fixing them until they break. This is a huge safety issue.

1. Brake accumulator pump is running too often, indicating that there is a pressure leak in the braking system. 2. As designed the pump will run only on occasion to charge the booster fully. This pump runs a lot, whether the car is running, or not, whether the brakes are applied, or not, and regardless of braking rigorously or gently. 3. Occasionally, on start up, brake pedal goes to the floor as the accumulator has lost all charge. 3. No brake warning lights on dash, yet. 4. No service codes known, yet. Toyota had a customer support program to address this issue, extending warranty to 10 years or 150,000 miles. I am at 160,000, 8 years. The problem has been occurring for a while, but I was not aware as it was my wife's car and driven solely by her. I was told today by a Toyota resolution specialist that no help would be forthcoming, and to hope that NHTSA issues a recall wherein my problem with the braking system would then be addressed. This seems problematic for many reasons, not the least of which is that it is regarding brakes, an integral part of the safety equipment to ensure our highways are without danger or have no known issues that have not been resolved by a car manufacturer. My Toyota case number is 230426001055. This 'complaint' is to alert this agency that there is a problem with my vehicle, and others, known by Toyota, as evidenced by past customer support program, and as substantiated today by service rep at family Toyota of burleson, and there is no recompense available for the $3,000. 00 repair required to ensure my vehicle safely travels our nations highways. While I understand that a car cannot be warrantied indefinitely, an eight year old car that has been meticulously maintained with a serious safety time bomb should not fall upon the owner entirely, nor should it be the responsibility of your agency to force the hand of the automaker. Since that is there stance, I appeal to you to respond seriously and help me try to remedy.

I bought this car brand new and have had it serviced regularly at a greensboro nc Toyota dealership. It has 127,000 miles on it. I starting hearing a grinding whirring noice a lot lately and determined it is a brake actuator/brake booster. Took it to the dealership and they confirmed it to be a brake booster going bad. Engages at least 4 times a minute. There is a customer support program for this repair from Toyota zjb and covers the part up to 10 years or 150,000 miles. I am in the covered period but it has to break first before they will cover it even though they confirmed it is going bad. It has to “throw a code” before Toyota will pay. I reached out totoyota and they reached out to the dealership which is greensboro Toyota in greensboro, nc and their regional office won’t fix it because it would come out of their pocket and Toyota won’t fix until it breaks. My research confirms this could be a bad safety issue driving around waiting for this to break. There are no codes yet but the dealership has heard it and confirmed it’s going bad and I have video of the part going bad. I always service everything with my car or home when it needs to be done and to be told to drive around until it breaks is negligent. Apparently it is a 2-3k fix. This is a serious safety issue that Toyota is aware of. Retha fisher 16 fawnwood CT greensboro, nc 27407 336-314-2000.

The brake assist. Driving and suddenly no brakes. Happened 2x in this vehicle and had to get a tow each time, even after getting new brake pads the first time it happened at my mechanics. The dealer confirmed today that they would fix the problem at $2700. The lights for traction and abs went off with a warning sound. Pulled over both times and called aaa for tow…. . Each a separate incident.

The brake booster pump assembly has failed through no fault of my own. This is a major safety issue!.

My mom was involved in an accident in her 2015 Toyota Prius on April 19, 2022, which she advised lurched forward at a stop and when applying the brakes to stop the vehicle, she said was unresponsive, causing her to clip a vehicle and sending her vehicle into a ditch totaling her car and injuring her passenger and her. I would like to have this investigated and hold Toyota responsible. This could have been much worse and lives could have been lost. She is now without means of transportation, and she is now possibly responsible for damages to property and bodily injury because of this. Through my research I have discovered multiple class action lawsuits brought against Toyota for the same exact models. I asked the police officer to run a scan on the computer, but he advised it was only for serious accidents. There was no indication of the problem or messages.

My 2015 Prius gen 3 has a 118,000 miles since we bought it brand new in 2015. We periodically have it maintained with our own mechanic even after the warranty expired with the dealer. However, we experienced that the lights of brake system, abs and vsc went out the same time. We have it checked but there was no error code. The car is operational but the brake system does not engaged fully when you presses the brake pedal. The vehicle does not stop immediately if you need to immediately stop the vehicle. The problem strongly indicates failure in abs control modules which can costs us a big amount of money ranging from $3,500 minimum up to $6000 max. Majority of the Prius owners that shared their experiences to us regarding the same problems are unanimous in their opinion that it is indeed the brake control module. That such defect can only be pointed to the manufacturers' misdeeds.

The contact owns a 2015 Toyota Prius. The contact stated that as he approached a stop light at 25 mph, the brake pedal was depressed and traveled to the floorboard as he attempted to stop the vehicle. The brakes failed to operate without warning as he hit the vehicle in front of him. The air bags did not deploy upon impact. A police report was filed and both the contact and the other driver were able to drive away from the scene. No injuries were reported. Prior to this failure, the contact stated that the same failure occurred months prior while traveling at 20 mph in the rain. The contact stated that the brakes failed to operate without warning as he depressed the brake pedal to the floorboard; he hit an unknown object on the road due to the failure. The contact initially thought that the failure was related to slippery roadways; however, after the most recent failure, he related the prior incident with his most recent failure. The dealer nor the manufacturer had yet to be notified of the failure. The vehicle had yet to be serviced or diagnosed. The failure mileage was approximately 80,000.

As stated from 5 months after we bought it, and the first Prius, the car won't start. No matter if parked flat, keys in or out over night, or the temp, when the break is pushed it is squishy and makes draining noise and won't start. As a dr on call I have lost patients because I could not leave my house. I carry and use the charger daily ever since. Taken in lots. They say, "you don't drive enough. . Or some other bogus excuse, like don't leave keys in car, which is how Priuses start and run!. The car is driven in all ways a lot. Also we buy headlights and headlamps on both about every 2 months. Also it looses power and has shut off while driving. The worst is when it would start on its own in the locked garage. At that point my wife just quit driving all together. Nothing but nightmares. She almsot crashed on fw when power went out.