general problems of the 2015 Toyota Prius - part 1

The brake booster pump has malfunctioned, exactly 1 year outside of the secondary coverage supplied in the voluntary customer support program for this exact issue, despite being under 150,000 miles. Now the car is unsafe to drive since the brakes are malfunctioning.

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.

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.

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.

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).

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.

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.

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.

I was driving my 2015 Prius for years and occasionally the brake, abs and traction light would come on this is a sign of a failing brake actuator and booster. Toyota and the ntsb ordered the following warranty enhancement https://static. Nhtsa. Gov/odi/tsbs/2020/mc-10181800-9999. Pdf my brake booster had been exhibiting signs of failing for years and I tried to get a Toyota dealership to replace and repair the parts under the warranty extension but I was told I had to wait until I had perminent dash lights and trouble codes. So I had to wait till the booster completely failed. By that time my car had exited the extended warranty perimeters and I am told it is no longer eligible. . . . Even though the components are faulty from the factory and exhibited signs of failure many years prior. I was told to wait until the compenent failed by multiple dealers. My car was in motion and the brake boosters failed, fortunatly it did not cause an accident but this is a serious safety issue. Toyota should have done a compleat recall of the brake actuator and booster pump, rather than have drivers use known faulty components until failure. Toyota corporate has refused to help in the repair of the vehicle despite it showing failure for years.

Code c1391 200k miles all the warning signs for brake booster issue came up. The cost is too high and I just missed the customer support program timelines because the code came up late. This needs to be a recall, based on how many people experience this issue consistently.

Abs braking system suddenly not working. Abs, brake, and traction control lights all turned on.

Toyota Prius has a known problem with the brake actuator and booster. A notice was sent out in 2019 under the customer support program expansion with repairs up to 10 years or 150k miles. This is a safety issue and should be covered under a recall with no time or mileage limits since these problems are not showing up until after 10 years if the car has low mileage, as in our case. We just passed the 10 year mark, but only has 114k miles. No mention of repairs needed were made during regular maintenance visits with Toyota. Additionally, preventative repairs were not offered if the vehicle did not seem to be experiencing problems at that time. The brakes are spongy and unresponsive. The abs light , traction warning lights, and parking brake lights are staying on.

On 4/16/26, while driving my 2015 Toyota Prius (approximately 87,000 miles) on the freeway, I applied the brakes while transitioning from the [xxx] onto the [xxx] . As I veered right on the curved onramp, the brakes failed to engage properly, causing the vehicle to spin out of control and collide with the side railing. There were fortunately no nearby vehicles on the 2-lane onramp at the time. Under slightly different circumstances, this incident could easily have resulted in serious injury or death to myself and/or others. No airbags deployed. Although I was physically unharmed, I was extremely shaken by the incident. Immediately after the collision, the brake warning light, abs warning light, and another warning indicator illuminated on the dashboard. Prior to the incident, I had not experienced braking problems severe enough to suggest imminent failure. On 4/17/26, I brought the vehicle to Toyota of cerritos for diagnostic evaluation. I was informed that the brake booster was the issue and that the vehicle was unsafe to drive. The vehicle was towed to a collision repair center affiliated with my insurance company. After repairing the external collision damage, the collision center informed me that the brake booster malfunction that caused the incident could not be repaired there and would require dealership service. External repair alone: $3706, in addition to increased automobile insurance premiums expected over the next 3 years. I also contacted Toyota motor corporation regarding customer support program coverage related to brake booster issues and was informed that the program expired in 2025 and no assistance would be provided. I am submitting this report because this brake booster malfunction created a serious and unexpected safety hazard resulting in loss of vehicle control on a freeway interchange. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

The incident involved having to press extremely hard on the brake pedal to stop the car, while it was uphill in the middle of the road. The car started going backward and was throwing abs, master warning light, brake system warning light and warning buzzer, brake system warning light, and slip indicator signals. This was a highly distraughtful situation on the road. Diagnostics showed c1391 diagnostic trouble code on the 2015 Toyota Prius: brake booster and brake booster pump problem. When pressing the brake pedal there is a high pitched metal scraping noise. Toyota coverage program is only applicable for 10 years from the date of first use or 150,000 miles, whichever occurs first. Many cars run well for over 10 years with good care, so the 10 year cap barely covers anything. This is highly unfair and borderline scamming for an issue so severe, which can cause big accidents on the road. In all honesty, this is a life or death situation when it comes to not being able to properly brake while driving. This should be a full recall!!.

My brake actuator and brake booster are failing. All of my dashboard lights have come on (brake, abs, traction control, brake system warning light). Unfortunately, I am over 10 years and Toyota is saying that I need to pay out of pocket for the repairs. This is a known problem and should be covered. I was unaware of the known issue and my car didn't start having problems until after the 10 year mark. I am under 150,000 miles.

Toyota Prius abs brake pump actuator booster failing making hissing noises and warning icon at only 10 years 9 month, 85,000 miles. Toyota extended warranty is not covering.

Brake booster and abs, brake master cylinder went out in car without any lights or warning while driving the vehicle at a moderate speed on freeway. I was able to avoid an accident and take the car to a repair shop in which at 119k miles and just at 10. 5 yrs old the entire brake system had to be replaced/repaired.

On Feb. 19, 2026, I went to an auto repair store to change oil. I was told that I need to have rear brake pad and rotor replacement service because my car does not have it. The mechanic showed me and said that I only have the front brake work and it can cause safety issue.

The brake booster suddenly fails at 54k mile. Brake responds slower and need to push the brake pedal all the way it seems a lot of 2010-2015 Prius are facing this problem abs light, skid light, and brake light was on when it happened, first appeared on Feb 6, 2026 have to replace brake boost for ~$1500.

Inferior brake system on 2015 Prius master brake cylinder and vacuum booster. Extended warranty issues identified by Toyota for 10 years or 150, 000 miles. I bought my Prius used in 2021 with 92,000 miles at age [xxx] old intending it to last as long as I did. I am now [xxx] old and essentially totally independent. The above mentioned parts were identified as not functioning properly on 2/3/2026 (mileage 139, 106). On 2/6/26, I took it to goettle Toyota, ocala FL (mileage. 139,160) knowing there was an extended warranty program available that was admitting the parts were defective but not worthy of recall. I was advised the warranty for my vehicle expired 10/26/2025 (3 months and 8 days prior) and was now invalid. Brake replacement cost is $3675. 00 + tax??. I was provided warranty information and instructed to call Toyota. I called, spoke with brook and was advised the warranty was invalid due to date even though the car has less than the 150, 000 mile covered and nothing could be done. I was never notified of this issue so I could monitor for problems before the expiration. Average life for these items on a Prius is 250,000 miles, not 139, 000. I am on limited, fixed income and cannot afford this unnecessary repair. I am already gladly driving a 10 year old car to be independent. Loss of transportation changes my entire lifestyle. I cannot afford another car (if I could, I would be fixing this one). I would be reliant for the rest of my life, on others for all needs outside of my home. I live in a very rural area. I feel since I was never notified of any issues and the car is low mileage and there should be another 100,000 miles on this car (I have driven it less than 50,000 miles in 5 years) that Toyota should honor the extended warranty based on the proximity of the malfunction to the ending of the warranty period and the low mileage of the vehicle. This amount of money is nothing to Toyota but it is life changing to this, up until now, independent woma information redacted pursuant to the freedom of infor.

Defected brake booster hard brake suddenly car less than 100 000 miles many vehicles with the problem.

I purchased a vehicle a year ago whenever my vehicle was still under the tenure and the 10 year and it’s still under 150,000 mile range. The vehicle was purchased strictly from the Toyota dealership in lakeland, florida, and shortly thereafter my brakes completely went out and the booster actuator assembly looking it up by further realize that is a very common issue and that there is so much that there’s class action lawsuits and also instead of it having a recall, it has a customer support to replace parts. My car is very dangerous and doesn’t have any brakes and it’s still very new from the dealership. What it’s very interesting is that it’s not throwing any codes at all, though it beeps the entire time that I’m in the vehicle with the abs light on and I know that it’s that problem why is it not showing any codes I think that for sure, the dealership would’ve had to done something to prevent that in order to sell the car unsafely.

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

The brake pump and actuator on my 2015 Prius has been faulty and the repair was apparently covered under the customer support program but it expired in December. I had no knowledge of it and when I took my car in to a Toyota dealership, no one told me about about the profram but told me that they needed to be replaced. I did not get the repair because of the hefty cost and I missed the deadline. My safety and the safety of other drivers were put at risk for not allowing me to be notified by it and my car being at risk for my brakes failing at any time. Their were absolutely no warning lights on my vehicle as well.

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 vehicle has 95k miles on it and both brake actuator assembly and booster pump have gone bad. This is a defective issue, I called Toyota and was told too bad since the program that fixed this ended 02/25. The car met the mileage requirement, but being 10 months out of the date gives Toyota the right to wash their hands on a defective part. The part is over $1500 just in parts to replace! this is wrong on their part. Not one option offered.

This vehicle has 95k miles, now the vehicle has a brake problem which can cause deadly problems. The parts that have gone bad on this car are defective parts that Toyota knows about. The warranty they extended for this ended in 02/2015. They had 150k miles or 10 years limit on that warranty. We are well under the mileage and 10 months over according to Toyota. Can’t believe they will dismiss something this delicate and dangerous. The parts are not cheap and it’s something we can’t afford to fix right now. I can’t believe Toyota will just wash their hands on something this important in a vehicle. This is a know defective part! they should have some sort of responsibility and resolution. I called and was told they cant do anything. Even a part offer so we can fix nothing. Please review this and hopefully you can help.

The brake accumulator went out thanksgiving day on my way home nearly causing an accident. I also missed dinner due to the issue creating a clearly unsafe driving condition where I was barely able to use my brakes. This is a known issue by Toyota, whom extended the warranty to 10 years. Of course, my warranty was 3 days past the 10 years even though it is under the mileage requirement. This should have been a recall, as it is a known and reported problem. I am now out 3300$ for the repair just to get my car in an operable condition. There were no warnings, the abs light as well as the traction alert went off and I lost the ability to properly brake in an instant. There was no warning, nor was I notified about this part.

The abs, break, and traction control, suddenly turned on when I was traveling on the freeway in mild traffic. I was traveling at about 60-65 mph. I attempted to use the breaks and could feel a substantial difference in how much and how hard I had to push in order to stop. The problem has not been confirmed by a dealer or service center. The vehicle was inspected by my brother in law who works on cars frequently. There were no warning symptoms prior to the problem. The problem first occurred on Saturday November 1st at about 12:30. According to my brother in law, it was the break pump that failed; you can hear air escaping when you push on the break pedal.

The contact owns a 2015 Toyota Prius. The contact stated that while driving approximately 15-20 mph, the abs, brakes, and the traction control warning lights, and the malfunction indicator light were illuminated. Additionally, the vehicle hesitated to respond while depressing the brake pedal, causing the braking distance to be extended. The vehicle was taken to the dealer, where it was diagnosed with an abnormal leak in the accumulator and a leak in the brake booster pump. The dealer determined that the brake master cylinder and the brake booster pump needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 94,100.

Emergency brake, traction and abs warning came on and stayed on in addition to a five-second interval cycling on of a motor sound under the hood. O'reilly auto parts and then Toyota dealership confirmed the same code that indicated brake booster assembly needs replacing (c1391) **this is a "known issue" but not yet a recall. Toyota did extend the part warranty to 10 years or 150,000 miles - my vehicle has only gone 85,500 and unfortunately is eight months into the 10th year and Toyota is refusing to cover any portion of the repair. I would like to be part of the effort to have this formally declared a recall because I got the quote today to replace the brake booster assembly and it's going to cost half the value of the vehicle! $4000 is the low estimate bighorn Toyota gave me to do the repair/replacement. Thank you for your help!.

Brake accumulator and master cylinder has failed. All lights for the abs, tsc, and vsc are iliuminated.

Got the warning code for c1391 for the brake booster. It failed at 140k miles but because it failed past the 10 year mark did not qualify for the Toyota extended warranty program. I don't think the warranty program is good enough and should be addressed as a recall. I had sudden total brake failure on the highway which could have been extremely deadly.

On or around 9/13/25 my abs, brake, traction and emergency sign sensors turned on in my 2015 Toyota Prius. I noticed that my brakes became squishy and when I drove, it took longer for my car to brake (there was more distance in my braking ability to stop the car). My car also felt a bit more airy than it usually does when I drive it. I took it to 2 independent car repair shops for a diagnostic and both told me that the abs c1391 code came up. Soon thereafter, I took it to a local Toyota dealership for a diagnostic and was given the abs c1391(code) abnormal leak in the accumulator. The Toyota mechanic informed me that that when he did the diagnostic, the TSB 0024-19 code came up on his end, which means that Toyota alerts their mechanics of the necessary procedures to implement for this problem, as it's a known Toyota problem and defect: 1) remove & replace the brake booster assembly w/the master cylinder (apparently the master cylinder goes out too since they're connected) and 2) remove and replace the brake booster assembly pump. Toyota's estimate to repair it is $4,404. 72; I can't afford this and need a car. It's my only car! I did research and learned that this is a known Toyota issue for Prius (2010-2015) and a customer support program w/an extended warranty was issued to cover the full cost. Despite this, their extended warranty expired for me on 12/29/24, despite me meeting the other 10 yr or 150k or less mileage criteria. Despite filing a complaint with Toyota's resolution center they refused to extend or offer warranty or any payment for a known Toyota defect, saying my issue was "after the extended warranty date" and there "isn't a recall. " I'm disgusted to say the least about this, as Toyota is well aware of this car part defect which is a safety hazard and liability for its customers. Something must be done about this. It's unfair and not equitable to have loyal Toyota customers absorb the cost of known safety hazard defects by Toyota and risk lives.

The brake booster system failed two weeks after the Toyota customer confidence program for that condition ended and they will not reimburse me for a $3000 repair. I knew there was a problem because all the dash lights came on at once while we were driving on a highway. I had it towed away to be repaired and it was found that the brake booster system was failing. Had I ignored it or not acted as immediately as I did the brakes could have failed while the car was in use and hurt or killed me or someone else. They should issue a recall for this condition and fix it for Prius models that still need it and they should reimburse me.