2014 Toyota Prius

The Toyota Prius, models through 2010 - 2015 have a known issue with the Brake Booster (actuator) and ABS Pump where the parts will degrade and break at or around 100,000mi. Toyota issued a bulletin and had a replacement program that covered the part that has since elapsed but has not corrected the issue with existing stock and inventory so the problem remains. When I purchased my car I was the 2nd owner, the car was purchased with roughly 160,000mi. The previous owner had informed me that he already replaced the actuator and ABS pump so I wouldn't have to worry about that repair. All told he said he spent $4000+ on the repair. When the car was driving I heard a high pitched whine. I took it to garages after my OBD tools could not identify the issue, no one had a fix and speculated that it was a power inverter and it was normal. Some weeks later, I was involved in an accident where the car did not stop in time, the brake went spongy and locked up, ABS failed to activate with no warnings or indicators. This is what first led me to suspect something wrong with the ABS. later the persistent whine was loud enough that I could identify that it was hydraulic in nature, pointing to the brakes. Within weeks the whine had stopped and my brake, ABS, and TCS lights came on, on the cluster. My OBD indicated that the ABS pump and Brake actuator were giving codes to the ECM. I replace it, and at about 240,000mi it went out again. Due to the extremely expensive nature of the part I purchased a used part which is now also bad. Toyota informed me that they have no intention of passing a recall notice or fixing the defective part. I would imagine that if the NHSTA looked into crashes involving this model and year group they would see an unusually high trend of these getting into an accident around 100,000mi increments. I believe that a recall should be issued due to the serious safety implications of potential defective cars on the road that may not be able to brake in time.

My vehicle is experiencing the well-known brake booster failure. This started at 90,000 miles, with an increased frequency in the running of the brake booster. It has steadily gotten worse, and now the pump runs with every brake application or every 13 seconds. There is now a hissing sound when I apply the brakes. I have repeatedly taken this to Toyota dealers and have been told: "The system is working as designed; no issues found". When I asked why the pump runs so frequently. No response. This is a $4,000 repair that Toyota should step up and fix. The next step in the degradation of this part is a loss of brake pressure. I tried resolving this matter with Toyota Corporate and was denied, even though my mileage is well below the extended coverage for this part of 150K miles and 10 years.

Facing brake booster/accumulator leak at ~105,000 miles diagnosed and confirmed by a mechanic at an independent service center. Problem is characterized by a hissing and chirping sound from the brakes. No warning lights appear on the dash, but this is a known problem with the 2014 Prius. Brake system could fail at any time, preventing the car from stopping. Repair of this system requires a >$2,500 payment. Toyota had an extended warranty up to 10 years after the car was purchased or before 150,000 miles. In this situation, the problem showed up after this time (2026), preventing compensation for repairs.

ABS and brake light are on. was on the freeway and when i pressed the brake the wheels got locked and the car made a 360 spin, it almost flipped over

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.

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.

My car experienced a failing brake actuator/accumulator. The first sign was the ABS and break lights accompanied by a whoosing sound. The issue causes intermittent system wide break failure and renders the car undriveable. Toyota had an extended warranty for this issue but that offer was closed by the time my car had the failure even though it was still under 150,000 miles. I believe this is a significant safety issue and should rise to the level of a recall by Toyota.

Brake actuator had been making noises and it finally stopped working on 7/14/26. Thankfully my car was and stopped and parked. The car has 137k miles on it, one owner and no explanation of what caused this. There were no accidents, abuse, or failure to maintenance.

The traction control, abs, and emergency brake light came on. We checked and the code produced was C1391. There’s a humming noise every 10 or so seconds when idle. The humming noise is also present when braking. We did some research and this appears to be an issue with Toyota Prius. We called the dealership and were informed that this was not a known issue. Thank you.

Car is at less than 105k miles and yet brake actuator is failing.

ABS, traction control, brake system, and brake lights turned on while driving. Took the car to the mechanic and pulled the code C1391. It seems from other complaints to NHTSA that it is a common issue and quite dangerous, meaning the brake system is failing.

ABS, brake, and traction warning lights came on. Loss of power brakes/limited manual brake. Extended warranty/customer service outreach did not apply. Car is at 120,000 miles and almost 12 years.

When the brake is applied, the vehicle accelerates for a fraction of a second before slowing down. I have experienced this when the vehicle is moving slowly, such as in a parking lot.

On April 5, 2026, while driving downhill around a corner in my 2014 Toyota Prius, the brake booster and brake booster pump assembly failed without any prior warning. When I pressed the brake pedal the car did not slow down and instead appeared to accelerate due to a complete loss of braking assist. I was unable to stop the vehicle normally and had to rely on gravity and coasting to slow down, creating a serious risk of collision. There were no warning signs prior to the failure. Immediately after the incident, three warning lights illuminated on the dashboard: the BRAKE light, the ABS light, and the VSC (vehicle stability control) light, which have remained on since. The vehicle was taken to DARCARS Toyota Baltimore, 6007 Eastern Ave, Baltimore, MD 21224, where the failure was confirmed on April 15, 2026. Technician Victor Lawson diagnosed diagnostic trouble code C1391, which is the exact qualifying code listed under Toyota's Customer Support Program ZJB for brake booster and brake booster pump assembly failure (RO# XXX). The vehicle remains at the dealership and is available for inspection. Toyota corporate was contacted and opened case number XXX but declined to cover the repair despite this being a documented issue that Toyota has publicly acknowledged. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

While driving, three warning lights suddenly appeared on the dashboard . Abs warning, traction light, and break warning light At the same time, the brake pedal became very hard to press, and the vehicle did not slow down as expected. This caused a significant increase in stopping distance, and I nearly rear-ended the vehicle in front of me. The issue appears to involve the braking system and created an immediate safety risk. No prior warning signs were noticed before this incident. The vehicle has not yet been inspected but is available for inspection upon request.

Subject: Brake Booster/Pump Assembly Failure – Toyota Program ZJB / 23TE07 Description of Incident: I am reporting a failure of the brake booster and pump assembly on my 3rd Generation Prius (82,000 miles). While the vehicle is 11.3 years old, it is well under the 150,000-mile threshold of Toyota’s Customer Support Program ZJB. The brake pump began cycling every 13 seconds, indicating an internal pressure leak in the accumulator. This is a documented precursor to a total loss of power-assist braking. Despite the clear mechanical failure, no warning lamps or Diagnostic Trouble Codes (DTCs) were triggered, creating a safety hazard where the system could fail without prior electronic notification. Repair and Cost Details: Because the vehicle was 1.3 years past the arbitrary 10-year "Secondary Coverage" window, I was forced to pay $3,461.18 out-of-pocket for a known manufacturing defect. I would like to highlight a discrepancy in labor billing: while Toyota’s own technical bulletins (ZJB/23TE07) state the repair should take approximately 5.3 hours, the dealership charged 8.9 hours of labor for the same procedure. Safety Concern: By limiting coverage to 10 years, Toyota has left many low-mileage owners with a critical safety defect that degrades over time regardless of mileage. I request that the NHTSA transition this from a "Customer Support Program" to a formal Safety Recall to ensure all affected vehicles are repaired and owners are reimbursed, regardless of the vehicle's age.

the cylinder head gasket blew because of the poor design of the intake manifold and the EGR system. There are updated parts to fix this issue, but there was no recall. This poor design led to the vehicle having "the Death Knock." It started doing this knock on my trip driving my daughter to college. The engine could have seized in traffic on the way to [XXX] from [XXX] . No warning lights came on telling me there was an issue. The vehicle is being taken apart now to see if my connecting rods were bent from the coolant entering the combustion chamber. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The contact owns a 2014 Toyota Prius. The contact stated that while driving at an undisclosed speed, the vehicle failed to slow down as intended with the brake pedal depressed. The ABS warning light was occasionally illuminated. The vehicle was pulled over to the shoulder of the roadway and restarted. The vehicle was taken to a local independent mechanic, where it was diagnosed, and determined that the brake master cylinder, brake booster, and brake lines needed to be replaced. The local dealer was contacted; however, the vehicle was not diagnosed or repaired. Upon further investigation, the contact related the failure to an undisclosed recall; however, the VIN was not included in the recall. The manufacturer was notified of the failure. The contact was referred to the NHTSA Hotline for assistance. The failure mileage was approximately 152,000.

Vehicle: 2014 Toyota Prius v Hybrid Mileage: 79,000 miles The vehicle experienced sudden failure of the brake booster / brake accumulator system. Multiple warning lights appeared including ABS, traction control, and the red brake warning light. Diagnostic code C1391 was retrieved. The brake pedal became soft/spongy and the electric brake pump began cycling frequently. Braking performance felt reduced and inconsistent, creating a potential safety risk. This vehicle has very low mileage (79,000 miles) and has been well maintained. The failure appears to be related to a known defect in the Prius braking system. Toyota previously issued Customer Support Program 20TE07 addressing brake booster and pump failures on 2012–2014 Prius v vehicles. Despite this known issue, the repair is not being covered and the cost quoted is several thousand dollars. A failure of the brake booster/accumulator system significantly affects braking performance and should not occur at this mileage. This appears to be a widespread issue affecting Prius vehicles and represents a potential safety defect involving the braking system.

Head gasket failure. No check, engine, light or warning. My car was very well maintained regularly. After research, I found this to be a very common problem. Yes it is available for inspection. Upon request. The problem was confirmed by chemical test, ignition vapors going into engine coolant. Other symptoms were misfiring on cylinder two and cylinder four. Severe engine knocking.