What 516 owners told NHTSA about the 2011 Toyota Prius

Vehicle Information: Year: 2011 Make: Toyota Model: Prius Mileage at Failure: 58,769 miles Date of First Use: February 20, 2012 Complaint Description: As I was driving on the freeway, my 2011 Toyota Prius brakelights all came on. I pulled off, had it towed to nearest mechanic, who diagnosed a failure involving the brake booster, brake actuator, and ABS system at only 58,769 miles. The vehicle was diagnosed with Diagnostic Trouble Code C1391 (Abnormal Leak of Accumulator Pressure). According to my mechanic, the condition is caused by an internal brake fluid leak within the brake booster assembly with master cylinder. The recommended repair includes replacement of both the brake booster assembly with master cylinder and the brake booster pump assembly. The estimated cost of repair is approximately $4,100. This concerns me because the brake system is a critical safety component, and I believe such a failure at fewer than 60,000 miles is highly unusual and may pose a safety risk to drivers and passengers. Toyota previously issued a Warranty Enhancement Program for this issue, but my vehicle was denied coverage because the program expired on August 31, 2021, and the secondary coverage expired on February 20, 2022, ten years after the vehicle's first use date. Toyota declined any out-of-warranty assistance despite the vehicle's exceptionally low mileage. I am submitting this complaint so that this incident is documented as a potential safety concern involving premature failure of the brake booster and ABS system components on the 2011 Toyota Prius.

NHTSA ODI 11746722

Shortly after purchasing used last year I had my brake, traction control, ABS, & TPMS lights come on when stopping at a stop light all at once. I went and had it scanned and no codes showed up. I hear a buzzing from the brake actuator/ brake pump every 15 seconds. This all has been going on for almost a year now. Over the weekend a loud buzzing warning alarm came on that will not turn off. I had it checked out and was quoted around 3500 to repair.

NHTSA ODI 11745016

The ABS actuator (brake booster) went out suddenly. It is 100% available for inspection. It is being towed to M&M Auto Repair in Gaston SC. I was not sure if the car was going to stop when I was trying to figure out what was wrong. The car was acting like it wasn't going to stop until a few seconds later. People online have had a similar problem as me with prius models around my year to 2015. And it was a problem confirmed by the dealership. The component has not been inspected. Only diagnostics were ran. The ABS system light came on. But it would disappear for a long time then come back. So I thought it was a computer error for the longest until it proved to not be one. Because the brakes were working just fine like normal. Other than that, the light itself was playing peekaboo with me, making me believe that it was a computer error since the brakes were working just fine. Then on monday, the car started beeping excessively and the brakes were not working suddenly after being fine over the weekend....with no issues.

NHTSA ODI 11744577

There is a known problem with the brake booster and skid control that was a part of an customer support extended recall program. Our Prius has very low miles (less that 60,000) so the issue didn't trigger for us until recently. Unfortunately, we are out of the extended recall program of 10 years or 150,000. This doesn't seem fair since it is a known and documented issue from Toyota. Unless we fix the issue, we are at risk of losing braking control. All brake lights on the dash are on and it is currently in the shop.

NHTSA ODI 11741498

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 ODI 11736723

I was driving my car and suddenly the traction , hand brake and ABS sign started showing up. I usually apply only 10% of force on brake pedal but after this I have to apply almost 60% of force to even slow down the car. Almost 90% force to stop the car It has threatened safety of my family. When diagnosed at autozone they told cannot determine error code. When reading in internet this seems to be common problem in prius. Please help is fixing the issue as it is not at my fault. This seems to be manufacturing defect.

NHTSA ODI 11734183

The brake cylinder assembly and the brake booster pump assembly failed while driving, which made braking very difficult, caused the regenerative braking to stop working, and caused multiple warning lights to come on. No warning lights, messages, or other symptoms were present prior to the sudden failure. This sudden failure could have easily resulted in a crash and/or death(s). I brought the vehicle to a Toyota dealership, and they confirmed the above issue and replaced the parts. I was told by the dealership, and also read online, that this is a known issue of Toyota for my vehicle and that Toyota extended a warranty years ago; however, the extended warranty is no longer valid for this known defect.

NHTSA ODI 11732836

Brake Booster went out right at 160000 miles. ABS, emergency parking light, tire pressure light, and others I'm not sure if went on. Brakes felt very mushy and scary to drive.

NHTSA ODI 11731718

While driving, the Brake, ABS, traction light and other light lit up. The car lurched in an odd way. I can hear the oil pressure pump turn on every 5 seconds. Toyota shops told me the master cylinder and booster pump are failing and that the brakes will stop working while driving, causing an accident.

NHTSA ODI 11714885

I was driving my car at over 70 mph on a highway, no check engine, no issues, just had oil changed when check hybrid system alert came on with check engine light. I started to change lanes to get to shoulder when my car just died, completely. It died in the middle of the highway merging with another major road, so I was stuck between 2 lanes of 70mph traffic on either side. The time to react to the sudden warning to my car dying was less than 2 minutes. I quickly called 911 to ask for help and was told someone had already reported my breakdown as well because my car had died in a horribly dangerous area. I was very lucky that a state trooper came quickly and blocked off my car until it could be towed for repair. I was told that I need a new Hybrid Battery. The fact that I had no signs of failure before complete shut down makes for a very dangerous driving situation and makes me second guess ever buying a Prius again.

NHTSA ODI 11711067

The abs, brake, and traction control are intermittently on and off recently. I thought that there was a visible leak in the brake fluid. But my mechanic said that there was no feasible leaks found upon inspection. The car has also been inspected in Maryland without any issues. I came across many forums that said that this is a common issue in Prius. My safety was at risk if this is due to internal failure or defect of the product, especially because I drive with my [XXX] almost everyday to take her to daycare. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11711037

ABS, Slip Indicator and Brake warning lights have appeared on the cars dashboard. DTC fault code C1391 has appeared indicating a failure of the Brake Booster and Brake Booster Pump assemblies per Toyota Customer Support Bulletin (ZJB) No.: POL18-03. Loss of regenerative braking, putting the safety off occupants at risk.

NHTSA ODI 11707419

The Master Cylinder started failing while I was driving the car, the car only has 138k miles, the dashboard lit up like a Christmas tree, all the warning lights were on, and when I went to step on the brake, I had to push it all the way to the floor for any braking to happen. I remember being scared for my life because I had almost no brakes which I could've got into a serious accident or been killed had it failed completely. I took the car to the dealer and they diagnosed it with code C139: Abnormal Leak at Accumulator Assembly, and recommended a new Brake Booster with Master Cylinder Assembly and Brake Booster Pump Assembly with Bracket. The car by age was not in Toyota's extended warranty on the parts but mileage-wise it still is, so I was footed with a $4-5k bill to replace both parts.

NHTSA ODI 11703999

I purchased a 2011 Prius 4 years ago from a dealership. For the last 2 years, whenever I drive the car, the ABS, brake, and skid lights are on. also, there's a slightly whirring noise every few seconds from under the hood. Braking has been affected, and I've had to increase my stopping distance as a result. Also, the brake pads and rotors deteriorate faster. Apparently, this is a common problem with this type of car. I've called Toyota, and despite it being a known flaw with this car, they refuse to do anything about it.

NHTSA ODI 11700201

VIN: [XXX] Year/Make/Model: 2011 Toyota Prius Mileage: 87,433 Date: 11/4/2025 DESCRIPTION Sudden 80% brake loss. Loss of ABS Brake Light + ABS + Traction Control lights on dash (photo attached). Known failed brake actuator (C1391) — identical to 500+ complaints in PE19-004. Toyota corporate denied coverage (email attached). This is a SAFETY RECALL issue — please reopen investigation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11697479

ABS Brake pump booster and actuator broke and got me almost into an accident. It's a known issue and it's a safety issue because car can still run but the brake is less sensitive. Please get Toyota to honor the repair.

NHTSA ODI 11697207

The ABS actuator on my 2011 Toyota Prius has failed, which is a known and common issue with this generation of Prius vehicles. The component causes abnormal brake pedal feel and inconsistent braking performance. The vehicle has been inspected and diagnosed by a Toyota dealership, who confirmed the ABS actuator assembly needs replacement. This failure poses a serious safety risk because it affects braking reliability and increases stopping distance, especially during sudden stops or wet road conditions. There were no warning lights or messages prior to the failure. The vehicle is available for inspection upon request. The problem has been confirmed by the dealership service department but has not been inspected by the manufacturer, police, or insurance representatives.

NHTSA ODI 11695108

Have continuous display of ABS , Brake lights for some time. Diagnosed as problems of ABS brake booster and pump. Toyota recognizes this issue but will not replace it.

NHTSA ODI 11693611

The contact owns a 2011 Toyota Prius. The contact stated that while driving at an undisclosed speed, the master warning light, ABS, and Brake warning lights illuminated. The vehicle was taken to an independent mechanic, who diagnosed failures with the brake master cylinder and the hydraulic accumulator. The vehicle was not repaired. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 95,000.

NHTSA ODI 11693462

Toyota issued a Customer Support Program ZJB for extended coverage of the brake booster and actuator assembly (this notice was not sent to the correct address the car was registered to with the dmv in 2019 so I never received the notice for this program) The Toyota program length was for 10 years or 150k miles. My car’s part just failed at 129k which is far below the 150k threshold. Despite being outside the 10 year window I am still under the mileage, the car is in perfect condition and this car is used for work for uber. The malfunction of the Toyota part in my car is a critical safety issue and because it is outside of the program Toyota refused to provide any goodwill assistance

NHTSA ODI 11681848

The contact owned a 2011 Toyota Prius. The contact stated while driving at an undisclosed speed in an intersection, a Ford F-150 vehicle crashed into the front driver's side of the vehicle. The contact stated he was pinned between the door and the infotainment system. The airbags failed to deploy. No warning lights were illuminated. The contact was taken to the local hospital by a friend in a private vehicle, and the contact received medical assistance. The contact sustained internal bruising and external bruising and cuts. Additionally, the contact sustained a major injury was on the neck, on the laryngeal prominence area of the neck and on the collar bone. The medical Doctor informed the contact that the major injury could heal in 4 weeks, or in 7-8 months. The contact was also informed that the major injury could become a permanent condition, causing cramps and stiffness depending on the weather. The contact was experiencing trouble sleeping due to the injuries. The vehicle was towed to a local tow lot and was totaled. A Police report was filed. The leasing company the vehicle was purchased from was notified of the failure. The contact related the failure to an unknown air bag recall. The manufacturer was not made aware of the failure. The failure mileage was approximately 325,000.

NHTSA ODI 11678773

I' m getting ABS warning light. Dealer confirmed that I need to replace Brake Actuator and Accumulator which costs me over $3K. Dealer refused to cover under warrant though it's a known issues with TOYOTA PRIUS vehicles.

NHTSA ODI 11675278

Odometer Fraud. The contact purchased a 2011 Toyota Prius. The contact stated that while attempting to register the vehicle, it was discovered that there was a mileage discrepancy. The vehicle was a dealer sale. At the time of purchase, the mileage was 145,000 and at the time of registration, it was discovered that the mileage was 227,000. The contact stated that while driving at 60 MPH, the check engine warning light illuminated. The contact took the vehicle to Auto Zone and was informed that the catalytic converter had failed and needed to be replaced. The contact was informed that it was not a new failure and that there was a possibility that the dealer may have removed the check engine light prior to the sale.

NHTSA ODI 11670893

Around 14 months ago (march 2024) I purcheded a replacment battery pack for our 2011 Toyota Prius form NexPower Energy (also going by, project lithium, sodiumhybrid) based out of CA. The battery pack is a lithum pack that replaces the orginal nickel metal hydride pack. In the beginning of June 2025, the car through an battery error and went into limp mode wile my wife was driving, when i go home and plugged in my scanner to check the battery out i noticed that the cells were out of balance and some were becoming very over charged. My fear is that if the cells were continued to be overcharged an thermal runaway event might occure due to BMS not being included with the overall pack.

NHTSA ODI 11667266

ABS warning system on dashboard is intermittent. I hear computer noises near the front driver tire. Then the warning light goes out or reappears on dashboard. Issue is the expensive diagnostic fee that may not unearth the cause, and if cause identified the diagnostic fee cannot be applied to the expensive repair. That’s a hard pill to swallow —and not affordable given economy, and I just had all four tires replaced along with a wheel alignment. Also, the yellow tire pressure light now blinks non-stop. (Previously it blinked 3x then stayed on but stopped blinking.) Anyways, Lots of covo about same issue in the 2011 Prius chat room I found after googling “2011 Toyota Prius ABS warning system.” Wondering if software needs updating, or perhaps there’s a systemic mfg defect?

NHTSA ODI 11667050