89 of the
15,583 complaints filed about the Toyota Prius
are about the driver-assist systems —
1% of everything owners reported.
The worst model year for it is 2010.
89
Complaints
1%
Share of all complaints
9
Crashes
0
Fires
Driver Assist & Collision Avoidance complaints by model year
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.
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.
NHTSA complaint #11748069 — an unverified report by a vehicle owner.
Dashboard Warning Lights: ABS, VSC, Parking Brake Light, Triangle with Exclamation Point, Codes: C1256 & C1391, Intermittent Audible Cabin Buzzing indicating critical pressure loss on start-up for about 10 seconds...then stops, not loss so much as anti-braking quick bursts at about 5 mph of stopping v slowly and seamlessly coming to a stop. I contacted Toyota Corporate Case Management; they refused to escalate or remediate the issue due to vehicle mileage, despite being notified of the active brake pressure leak codes and the audible safety alarm.
NHTSA complaint #11744740 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11741205 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11740166 — an unverified report by a vehicle owner.
2011 Prius. 80k miles. Brake booster buzz coming on every 15 seconds now. ABs, traction and brake lights on. I’ve heard of many Prius owners with the same issue. I also have another Prius with the same issue at 120k miles. Brake booster accumulator codes popping up with 80k miles. It is a safety concern as the abs brakes don’t work. Almost every Prius is effected by this.
NHTSA complaint #11736723 — an unverified report by a vehicle owner.
Year/Make/Model: 2013 Toyota Prius • Component: Brake Booster Assembly with Master Cylinder (Part #47070-47060) Description of the Defect: After approximately 30–40 minutes of driving, my dashboard illuminates with the Brake, ABS, and VSC warning lights simultaneously. The brake pedal becomes inconsistent and requires significantly more effort to stop the vehicle. This is a known internal fluid leak within the brake booster assembly that causes the accumulator pump to run continuously and ultimately reduces braking performance — a direct safety hazard. Why This Requires Federal Attention: This is not an isolated incident. Hundreds of 2013 Prius owners have reported identical symptoms, with associated diagnostic trouble codes C1391, C1252, C1256, and C1253. Toyota acknowledged this defect by issuing Technical Service Bulletin TSB-0089-20 and a Customer Support Program (ZJB) providing limited extended warranty coverage. However, that program was not well publicized . I was never informed as a vehicle owner . And it has now expired, leaving thousands of owners with a dangerous defect and repair bills costing thousands . A safety defect of this magnitude — one that can result in sudden, significant loss of braking ability — should not have an expiration date on its remedy. Toyota has not issued a mandatory recall, and owners continue to unknowingly drive vehicles with compromised brake systems. Requested Action: I respectfully urge NHTSA to: 1.Open a formal investigation into this defect across all affected 2013–2015 Toyota Prius model years 2.Require Toyota to issue a mandatory safety recall 3.Compel Toyota to cover repair costs for all affected owners regardless of mileage or age of vehicle
NHTSA complaint #11736173 — an unverified report by a vehicle owner.
Brake actuator is broken. Toyota knew about this problem and they had a warranty for 10 years or 150k miles. Mine only has 80k miles. The repair is half of what the car is worth. I thought a Toyota with such low miles would be dependable. Toyota knew that people have died from this problem with their car. I need this car to get to work and get my kids to school. It’s older than 10 years so I am just screwed on something they knew was broken. Of course the sales person at the Toyota dealership did not tell us about it when he sold us the car
NHTSA complaint #11733751 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11725874 — an unverified report by a vehicle owner.
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 ,
NHTSA complaint #11723750 — an unverified report by a vehicle owner.
On August 15, 2025, I was backing my vehicle when the rear view camera screen went blank, providing no image of what was behind me. With no warning and no image, I collided with a rock and landscape, causing damage to the rear of my vehicle. At the time of this incident, my vehicle had an open, unrepaired safety defect under Safety Recall 25TA13, which specifically addresses the condition that the rear view camera image may freeze or not display while reversing. I was not aware the recall existed at the time of my accident, and the recall remedy was not completed on my vehicle until February 12, 2026 — nearly six months after the incident. I filed a claim with Toyota Motor North America. They inspected the vehicle on February 11, 2026, found the camera functioning at that time (after the recall had since been remedied), and denied my claim. They cited owner's manual language advising drivers not to rely solely on the backup camera, but did not address the fact that the recall was unrepaired at the time of the accident. Additionally the parking collision warning and automatic braking should have engaged. The rock impacted the car right near one of the car cameras....so the collision warning and braking should have engaged. I am filing this complaint because I believe the unrepaired recall directly caused my inability to see behind my vehicle, and that Toyota's delay in notifying me and completing the remedy contributed to this incident. I am requesting that NHTSA review whether Toyota's notification and remedy timeline for Recall 25TA13 was adequate, and that this incident be added to the record of complaints associated with that recall.
NHTSA complaint #11723621 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11711995 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11710539 — an unverified report by a vehicle owner.
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.
NHTSA complaint #11707101 — an unverified report by a vehicle owner.
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 on: 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)
NHTSA complaint #11703465 — an unverified report by a vehicle owner.
Infotainment screen stuck on "Experience Drive Connect" screen which disables all the safety devices on the vehiucle. OEM needs to update the software to remove this screen. Screen is tied to Toyota subscription service. I believe all new Toyota products would have this vulnerability.
NHTSA complaint #11697030 — an unverified report by a vehicle owner.
Infotainment screen stuck on "Experience Drive Connect" screen which disables all the safety devices on the vehiucle. OEM needs to update the software to remove this screen. Screen is tied to Toyota subscription service. I believe all new Toyota products would have this vulnerability.
NHTSA complaint #11697030 — an unverified report by a vehicle owner.
FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL
Infotainment screen stuck on "Experience Drive Connect" screen which disables all the safety devices on the vehiucle. OEM needs to update the software to remove this screen. Screen is tied to Toyota subscription service. I believe all new Toyota products would have this vulnerability.
NHTSA complaint #11697030 — an unverified report by a vehicle owner.
Since October 2023, my 2019 Toyota Prius has developed severe and unpredictable driving behavior after a regular brake service, which may have triggered or coincided with a software or ECU update. The car, which had been driving smoothly since I bought it in 2021, suddenly began showing false braking, steering interference, and lane instability — as if the car were trying to “correct” problems that didn’t exist. These interventions often happen on highways or during turns, creating serious safety risks for both driver and passengers. I’ve spent months and thousands of dollars replacing parts, performing alignments, and recalibrating sensors, including at Toyota dealerships. The problem persists because it is software-based, not mechanical. I discovered that in mid–2023, the NHTSA announced upcoming rules requiring Automatic Emergency Braking (AEB) with pedestrian detection by 2029. Around that same time, reports from multiple drivers (Toyota, Honda, Hyundai, Ford, Subaru) began to appear describing the exact same issues. It seems manufacturers began silently updating vehicles to meet anticipated compliance standards. However, this introduced overly sensitive and malfunctioning driver-assist systems. The most alarming part is that the driver cannot fully disable these features — the “off” button only reduces their intervention. This means when the system malfunctions, the driver is forced to operate an unsafe vehicle. As a professional rideshare driver, this problem destroyed my ability to work. Passengers reported me for unsafe driving because of the car’s erratic behavior. I eventually lost my vehicle and income. I believe this is a systemic safety defect linked to premature or unregulated implementation of AEB software. Drivers deserve the right to fully disable malfunctioning systems that endanger lives. This is not just a car issue — it’s a public safety crisis that must be urgently investigated.
NHTSA complaint #11692652 — an unverified report by a vehicle owner.