2011 Toyota Prius

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.

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.

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.

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.

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.

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)

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)

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.

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

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.

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.

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?

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.

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.

My ability to break unexpectedly stopped working while I was on the highway during morning, rush-hour. I was going 55 mph on the highway at the time and luckily, I was on an uphill incline when they went out, thus allowing me to be able to ‘naturally’ slow down. But had I not been on an incline at that time of the brakes faulting, I would have 100% caused a wreck because I could not break at all. My emergency breaks weren’t even working, which is confusing because I thought that was the whole point of the emergency break, was for if your regular brakes become faulty… But NONE of my brakes worked. Which has created a new fear I didn’t know could happen while driving… Also, all the lights that have to do with the breaking system were on (ABS, Traction control, BREAK lights). And a consistent building up hissing noise under the hood.

Our trac abs and brake lights came on and braking became more difficult but not totally gone. I took it to my mechanic (not Toyota dealer) and he said the codes were going off for the abs hydraulic system and it would be $3000 to fix! This is unacceptable. I feel like my safety is affected but no one else has been hurt YET. I’m trying to be proactive. they first appeared last month. No manufacturer, insurance agent or cop has inspected it. It can be inspected by appt. Please help

ABS actuator and pump failure

Brake warning came on and wouldn’t go off. Followed by continuous beeping and now the brakes are no longer working properly. You have to force the brake all the way to the ground to even come to a rolling stop. The problem first occurred on 3/8/25. The brake actuator seems to be a reoccurring problem that Toyota addressed but is no longer fixing. It is dangerous to drive my vehicle and others have said their brakes have completely failed when this problem arose.

My brakes suddenly stopped responding correctly as I was pulling up to a busy road. My car went part way into traffic and I was nearly hit. After speaking to my mechanic and my local Toyota dealership, I was informed that there was a know issue with the Brake Booster and Hydraulic Accumulator on this vehicle and that Toyota had extended the warranty several times but that it no longer covered my vehicle. They never once acknowledged the safety issue and I was never notified of the risk. I believe the extended warranty was setup to avoid a recall and hide the risk. I firmly believe a recall should be done on these parts and owners should be notified of known safety risks this presents.

There were not any prior problem with my 2011 Toyota Prius' brake but it started making air pumping noises when I brake which makes me very nervous to drive my car. A local mechanic confirmed that the problem is the faulty brake booster assembly and pump. Toyota issued Customer Support Program for this problem but covered only up to 10 years from the first date of use. Although my car has less than 120,000 mileage, I have to pay for this repair and it will cost me close to $2500 at a local repair shop! I want to go to Toyota dealership to fix but their cost is going to be even more! According to online research, many Prius owners have this same problem and have to pay out of their own pockets. This is unacceptable. Toyota should put a recall on this problem and cover the repair cost!!