4,578 of the
15,604 complaints filed about the Toyota Prius
are about the braking system —
100% of everything owners reported.
The worst model year for it is 2010.
I am filing this complaint to report an active, severe safety defect involving a sudden, un-warned loss of power braking assist due to a failing factory brake actuator/booster pump assembly. My vehicle is exhibiting the exact internal hydraulic seal failure, pressure drop, and audible hissing/sipping sound outlined in Toyota's prior technical service bulletins. Because the onboard ECU computer only triggers warning lights once a complete, catastrophic failure threshold is met, the system is currently masking the defect from the dashboard. However, the physical hardware is actively failing, requiring the high-pressure pump to run constantly to maintain braking pressure. This component failure dramatically increases stopping distances and presents an immediate, unreasonable risk of a crash. Toyota previously acknowledged this widespread manufacturing defect via Customer Support Program ZJB (20TA02). However, because Toyota chose to manage this critical safety hazard through a time-limited warranty extension rather than a mandatory safety recall, hundreds of thousands of vehicles are now left with a catastrophic braking hazard because the consumer coverage expired in 2022. I urge the NHTSA to open a formal defect petition review to investigate these post-warranty failures and mandate a retroactive safety recall to protect the public.
NHTSA complaint #11764198 — an unverified report by a vehicle owner.
Subject: Vehicle Safety Defect Complaint / Request for Investigation Review Vehicle: 2010 Toyota Prius VIN: [XXX] Component: Electronic Brake Booster / Pressure Accumulator Assembly Dear Administrator, I am writing to formally report a critical safety defect in my 2010 Toyota Prius regarding the electronic brake booster and accumulator pump assembly. This component exhibits classic failure symptoms—specifically a distinct puffing, ticking, and pressure-loss noise directly from the brake pedal mechanism—which points to internal nitrogen or hydraulic pressure leakage. This component was previously the subject of Toyota’s Customer Support Program / Safety Recall (Campaign ZJB / D0H) due to fatigue cracking in the internal accumulator bladder. However, Toyota's arbitrary cutoff timelines have left me completely unprotected, even though the underlying engineering defect remains identical and poses an active, catastrophic threat to public safety. The real-world implications of this failure are severe: •Daily Risk to Life: I am a self-employed small-business owner who relies on this vehicle daily to travel between clients across the greater [XXX] area. Because of this failing component, I experience profound fear every single time I drive that I will completely lose my brakes in heavy traffic. •Financial Barrier to Remedy: Authorized Toyota dealerships have quoted me several thousand dollars for the repair. Due to a 40% drop in my business income amid the soaring cost of living in [XXX], I cannot afford this repair, nor can I afford a rental car or alternative transportation. My car is my literal lifeline, forcing me to drive a vehicle with a compromised, safety-critical braking system. •Unfair Expiration of Safety Remedies: My vehicle was serviced by authorized Toyota dealerships twice during the active primary campaign window (on XXX at 36,675 miles, on 08/30/2019 at 41,238 miles), where recall status checks were routinely requested INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(
NHTSA complaint #11763884 — an unverified report by a vehicle owner.
The contact owns a 2013 Toyota Prius. The contact stated that while driving 60 MPH, the ABS warning light illuminated. Minutes later, the vehicle started to brake and lurch forward with the accelerator pedal depressed. The contact stated that the vehicle spun out and crashed into the median. The contact’s chest struck the steering wheel, causing bruising and chest pain. The contact was managing the pain with analgesics. The vehicle was towed to an impound lot and was deemed a total loss by the insurance company. A Police report was filed, but the report number was not provided. The manufacturer was contacted and was made aware of the failure. The failure mileage was approximately 140,000.
NHTSA complaint #11763340 — an unverified report by a vehicle owner.
While driving my 2014 Toyota Prius, the BRAKE, ABS, and vehicle stability/traction control warning lights illuminated. There was no crash, injury, or noticeable loss of braking before the warnings appeared, and there were no preceding symptoms. The vehicle was evaluated by Mac Haik Toyota in League City, TX, an authorized Toyota dealer. They diagnosed DTC C1391, “Abnormal Leak of Accumulator,” and determined that the brake booster and brake booster pump/accumulator assembly require replacement. The dealer advised that the vehicle cannot be driven and is considered down. The vehicle/components are available for inspection upon request. My safety concern is that this is a brake-system malfunction serious enough that an authorized Toyota dealer has determined the vehicle cannot be driven. Toyota previously established Customer Support Program ZJB addressing internal malfunctions of the brake booster and brake booster pump assemblies in 2011–2015 Prius vehicles. Toyota’s documentation specifically identifies C1391 as a diagnostic code associated with this condition. My Prius has only approximately 102,000 miles, well below the program’s 150,000-mile limitation, but is outside its 10-year time limitation. The Toyota replacement part required to repair the brake system is now backordered with no known timeframe for availability. Because Toyota has advised the vehicle cannot be driven, it will remain out of service until the part becomes available. I am reporting this because a previously identified brake-system failure continues to occur after Toyota’s support period expires. I ask NHTSA to consider whether continued C1391 brake booster/accumulator failures in these Prius vehicles warrant further investigation or safety action.
NHTSA complaint #11762180 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11760825 — an unverified report by a vehicle owner.
Component failed: Brake actuator and accumulator on a 2010 Toyota Prius. It is available for inspection upon request. Safety: ABS, traction, and brake lights turned on suddenly in the middle of rush-hour traffic, followed by a spongey, hard-to-press pedal. Braking distance and efficiency was greatly impacted, and driving to a safe turn-out was extremely dangerous as I feared the brakes would give out entirely at any moment. The problem has been reproduced and confirmed by a dealership. UNKNOWN. Requested an inspection by the manufacturer but their "Customer Support Program" for the brake actuator and accumulator expired 10 years after the car's production date. After speaking to both the dealership and corporate, they have informed me that there is nothing else they can do in regards to reimbursement or satisfying the complaint. The only symptom of the problem prior to failure was a periodic hissing noise coming from the brakes. When the car was brought in for the catalytic converter in late 2025, the dealership failed to diagnose any issue with the brake booster system at that time.
NHTSA complaint #11760155 — an unverified report by a vehicle owner.
The break pump for my 2013 prius is going out and is a known issue with Toyota. I contacted toyota and they have stated because it is past the extended warranty they can not repair it and aren't liable for it. I bought the car used and was unaware that it has been a known issue for years. The previous owner did not have it replaced as they were probably unaware as well. It is a highly unsafe issue and has caused my breaks to suddenly go our while driving recently with my toddler. It is also $3000-$5000 to fix it and is almost more than the cars value. I need help resolving this as it isn't "normal wear and tear" or a mileage issue. It is a known, very public defect that toyota has admitted and I have been able to easily find information on all over Google. The warning lights came on out of no where on the freeway today.
NHTSA complaint #11759613 — an unverified report by a vehicle owner.
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)
NHTSA complaint #11759804 — an unverified report by a vehicle owner.
To Whom It May Concern, I am writing to formally complain about the way Toyota has handled the problems with my 2010 Toyota Prius and my repeated requests for assistance. I have been a loyal Toyota customer and have purchased two new Toyota vehicles because I trusted Toyota's quality and expected good customer service. Unfortunately, after years of contacting Toyota, I have repeatedly been given the runaround without receiving a meaningful resolution. I am now facing a serious and expensive brake system problem. The vehicle requires replacement of the brake booster with master cylinder and the brake booster vacuum pump, with an estimated repair cost of approximately $4,000. This is a major safety-related repair, and I believe Toyota should properly investigate the issue and consider warranty coverage or financial assistance. I am also experiencing a serious problem with the paint, which is melting/deteriorating. I have contacted Toyota about these issues before, but the company has not provided the assistance I expected. It is extremely disappointing that after purchasing two new Toyota vehicles, this is the type of customer service I have received. I should not have to repeatedly contact Toyota or file complaints before my concerns are taken seriously. I am requesting that Toyota review my vehicle's history, my previous complaints, the brake system failure, and the paint problem and provide a fair resolution, including consideration of reimbursement or assistance with the approximately $4,000 brake repair. I hope Toyota will take this matter seriously and respond in writing. If Toyota is unwilling to resolve these issues, I will consider escalating my complaint to the appropriate consumer-protection and regulatory agencies.
NHTSA complaint #11759364 — an unverified report by a vehicle owner.
I purchased a 2013 Toyota Prius from a reputable dealership in Omaha (O'Daniel Honda). 5 days after purchase the ABS, BRAKE, and Traction Control lights came on in the evening. When I took it to the dealership the next day they had cycled off and the dealership couldn't find anything wrong. A few days later it happened again so I got into the dealer right away and they said Toyota had issued a service bulletin C1391 in 2019, and that I would have to replace the brake booster, brake cylinder, and brake pump assembly. I'm still fighting with the dealership to make this right, because they should have caught this during their inspection before putting the car for sale on their lot. The indicator lights keep cycling on and off. Something that effects the braking system should be a recall and not a service bulletin.
NHTSA complaint #11759367 — an unverified report by a vehicle owner.
The contact owns a 2013 Toyota Prius. The contact stated that while driving at an undisclosed speed, the ABS, traction control, and BRAKE warning lights were illuminated. The contact pulled off on the off-ramp and became aware that extra effort was needed to depress the brake pedal. The vehicle was towed to the dealer and was diagnosed with brake booster and accumulator failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 120,000.
NHTSA complaint #11756742 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11756229 — an unverified report by a vehicle owner.
Vehicle Information: 2011 Toyota Prius, 144,000 miles. Component: Hydraulic Service Brakes, Electronic Stability Control, Anti-lock Braking System. Description of Incident: While driving at normal speeds, the vehicle suddenly experienced a severe reduction in braking capability. The dashboard simultaneously illuminated the Brake Warning Light, ABS Light, and Slip/Traction Control Indicator Light. The brake pedal immediately became soft, spongy, and squishy, requiring significantly increased physical foot pressure and a vastly extended distance to bring the vehicle to a stop. Upon inspection, the brake fluid reservoir remains completely full, but the brake booster pump under the hood cycles and buzzes rapidly every 10 seconds while stationary. A diagnostic scan confirmed trouble code C1391 (Brake Actuator Internal Leak). This indicates a severe internal hydraulic pressure bleed inside the braking module. [SEE ATTACHED] This is a known, widespread manufacturing defect previously documented under Toyota Customer Support Program ZJB. The manufacturer has refused to remedy this life-threatening safety defect because a 10-year calendar threshold has passed, despite the vehicle being well under the 150,000-mile limit established by the manufacturer. The vehicle currently poses an immediate safety risk to occupants and the public.
NHTSA complaint #11756097 — an unverified report by a vehicle owner.
My vehicle has 105492 miles and ABS light, Trackion and Brake light went on. I could hear a buzzing sound from the brake actuator every 5 seconds. The brake actuator and master cylinder was failing. According to the dealership failure of brake actuator and master cylinder is a common safety issue with Toyota Prius. The failure of the actuator can lead to failure in the braking system and a crash. Online research shows that several customers have reported this issue. The Claremont Toyota quoted me $3646 to fix this issue. I contacted Toyota of America and they informed that they cannot cover these repairs case number 260515002576.I took my vehicle to a private mechanic. I paid $2312 for parts and labor to fix this safety issue. I would like to file a complaint against Toyota for not addressing this critical safety issue.
NHTSA complaint #11755768 — an unverified report by a vehicle owner.
I am submitting this complaint regarding a serious safety concern involving the brake actuator/booster assembly on my 2014 Toyota Prius. My vehicle has experienced failure of this critical braking component and has been unable to be properly repaired since November due to difficulty obtaining the correct replacement parts. This involves a major safety system required for proper braking operation. Brake actuator/booster assembly. Diagnostic codes: B1206, B2321, C1252, C1253 C1256. Toyota previously acknowledged brake actuator concerns through Customer Support Program ZJB. However, my vehicle is outside the program limits despite experiencing what appears to be the same type of failure reported by many other Prius owners. Since November, I have faced difficulty obtaining the correct parts, reports of nationwide backorders or limited availability, conflicting information regarding updated Toyota part numbers, and concerns about repair providers advertising new OEM parts that may actually be aftermarket or incorrect components. This creates a safety concern because owners experiencing brake failures may be unable to obtain timely repairs using verified, appropriate parts. Repair estimates have ranged from approximately $3,000 to over $4,000, including a Toyota dealership estimate of approximately $4,100. This creates a significant barrier to restoring a vehicle to safe operation, especially involving a component Toyota has previously addressed through a customer support program. I request that NHTSA review this complaint and similar reports to determine whether further investigation is warranted regarding Toyota Prius brake actuator failures, parts availability issues, and whether additional manufacturer action or support is needed. A vehicle’s braking system is a fundamental safety component. Owners should be able to obtain a safe and reliable repair without months of delay or uncertainty regarding replacement parts.
NHTSA complaint #11754349 — an unverified report by a vehicle owner.
I am the first owner of a Toyota 2013 Prius that I purchased in Baltimore, MD, in 2013. I moved Georgia in 2014. The car currently has 130000 miles. I heard there were recalls on this vehicle type few years ago, but I was never notified. The brake has failed recently with code C1391. I spent $3,500 recently and the car is still in the repair shop.
NHTSA complaint #11753299 — an unverified report by a vehicle owner.
Every time I'd press the brakes there'd be an audible "click" noise and then when taking my foot off the brake it'd sound like a manual tire pump being pressed... kind of like air filling / hydraulic sound. This worried me (I don't mess around with brakes). One other thing that would happen is if I pressed the brake hard enough, the automatic braking system would kick in. The Toyota dealership claimed they couldn't hear anything and there were no warning lights so I took it to a reputable local mechanic. They diagnosed it as a bad ABS Actuator / Brake Booster and said it's common with this year of Prius. They also said it was good I brought it in now because it was not severe enough to totally fail (which could have caused an accident) but there was evidence of degradation and they also said the issue was causing sufficient brake fluid to not get where it needs to be.
NHTSA complaint #11752939 — an unverified report by a vehicle owner.
Code 1391 / power brake booster failure. Know defect by Toyota in which they extended warranty, vehicle is within mileage warranty but past the date warranty. Therefore Toyota will not assist in repairing. Very troubling in that this is a high risk recall or safety issue well known and instead of repairing extended. Repairs cost more than half the value of the vehicle and we are heavily reliant on this car and cannot afford 4k repair nor would sell knowing the saftey issue. Apparently there was notices sent for voluntary repairs in which I never received, had I received and reviewed I would have had repaired. My car had been to Toyota dealership and was never notified of this recall. Toyota offered voluntary programs (such as ZJB or model-specific extensions like 21TE01 for certain 2012–2014 Prius c vehicles) to replace failing brake boosters and pump assemblies.
NHTSA complaint #11752316 — an unverified report by a vehicle owner.