2011 Toyota Prius Brakes Problems

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 ID

11756097

Incident

Aug 7, 2026

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 ID

11752939

Incident

Jul 1, 2023

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 ID

11746722

Incident

Jan 15, 2026

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 ID

11745016

Incident

Dec 31, 1969

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 ID

11744577

Incident

Jun 15, 2026

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 ID

11741498

Incident

May 29, 2026

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 ID

11736723

Incident

May 9, 2026

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 ID

11734183

Incident

Apr 25, 2026

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 ID

11732836

Incident

Mar 19, 2026

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 ID

11731718

Incident

Apr 6, 2026

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 ID

11714885

Incident

Jan 30, 2026

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 ID

11711037

Incident

Nov 7, 2025

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 ID

11707419

Incident

Dec 17, 2025

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 ID

11703999

Incident

Nov 25, 2025

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 ID

11700201

Incident

Mar 3, 2023

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 ID

11697479

Incident

Nov 4, 2025

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 ID

11697207

Incident

Oct 1, 2025

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 ID

11695108

Incident

Oct 30, 2021

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 ID

11693611

Incident

Oct 18, 2024

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 ID

11693462

Incident

Oct 15, 2023

Mileage

95,000 mi

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 ID

11681848

Incident

Aug 18, 2025

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 ID

11675278

Incident

Jun 2, 2025

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 ID

11667050

Incident

Jun 15, 2025

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.

NHTSA ID

11660213

Incident

May 6, 2025

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

NHTSA ID

11659010

Incident

Apr 15, 2025