2011 Toyota Prius Brakes Problems

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.

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a known issue of Toyota for my vehicle and that Toyota extended a warranty years ago; however, the extended warranty is no longer valid for this known defect.

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.

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.

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?

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.

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!!

While driving on the interstate, the "brake", "TCS", and "ABS" lamps lit up. The brake pedal was stiff and couldn't be depressed. The vehicle initially did not decelerate while attempting to push down on the brake pedal. While maneuvering off the interstate on to the exit lane, the pedal remained stiff however, the vehicle did begin to decelerate. Critically, the amount of time needed to bring the vehicle to a stop was significantly longer than normal. This brake failure could have resulted in a catastrophic, life threatening and/or deadly accident. The DTC associated with this brake booster and pump failure is C1391 which is referenced in TSB-0024-19. This is a known problem that exists in Priuses manufactured between 2010-2015 and addressed by Toyota with CSP(s). The CSP takes a reactive approach to this serious safety concern as owners who "have not experienced the condition described" were informed that "there is no action necessary at this time". The extended warranty of 10 years or 150,000 miles is not applicable to countless drivers who are experiencing this failure caused by "internal malfunctions" outside of this arbitrary time/mileage frame. A letter was sent to the NHTSA on 9/19/19 by the president of Claremont and Capistrano Toyota to petition for the initiation of a Defect Investigation regarding this issue. The letter notes that this brake defect is "causing crashes that are injuring people- and Toyota is mishandling it". The advisor assigned to this repair estimated that they see this issue 1-2 times a month and increasingly, drivers are not covered by the CSP. Toyota is failing to take a proactive approach to this dangerous safety issue by telling owners to essentially wait and see if they experience this failure and then failing to take responsibility for said costly failure should it occur outside of their arbitrary time/mileage frame. This approach to safety is egregious, irresponsible, and unethical and it is putting countless lives at risk.

I have been doing some research, and the brake actuator and ABS system failing is a common problem on these cars. Mine recently started acting up and they used to replace it for free. I got my Prius only 6 months ago and have not had any luck getting Toyota to replace it. This needs to be recalled it is a serious safety hazard if the brakes suddenly give out. They should be replacing this free on all cars having this issues and they are aware of the issue (Toyota). The brakes suddenly stopped working well and lights came on in this exact instant on the interstate. This first happened about a month ago. Tons of people are making complaints with the NHTSA for the same issue.

All brake lights on Dashboard came on. Almost got into an accident because brakes were not responding. Brakes started responding but lights remained on. At time it will contibue to beep and Brakes do not respond. I am seeing that this is a common issue happening to most Prius vehicles after a certain period. It is extremely expensive to repair. Since this is happening on quite a lot of Prius vehicles, I feel this should still be covered by Toyota. This appears to be a faulty Brake Pump and Brake Booster. This has not been inspected by a dealer but being that the car is a 2011, I'm afraid they will decline from what I have been reading.

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.

What component or system failed: 47070-47060 Pump Assy, Brake Booster w/Accumulator yes 47050-47150 Cylinder Assembly, Brake Master with Fluid yes put at risk: yes - abnormal braking ABS failure-traction control loss Has the problem been reproduced or confirmed by a dealer: yes Has the vehicle or component been inspected by the manufacturer: Not my specific parts Were there any warning lamps: Yes abs, traction control

The brake booster has failed. I was driving, and the ABS, Brake, and Traction Control lights suddenly came on. The brakes felt less powerful. I drove the car Broadway Toyota in Portland, Oregon for maintenance. I was told that the system has failed, and while this is a known issue. It is not currently covered. I was also told that the car is not safe to drive. Toyota had a "Customer Support Program" to cover this issue. However, the program expired on Oct. 8th, 2021. Had I known, I would have brought it in prior to the expiration date. This seems like a recall issue. In Toyota's paperwork for the Customer Support Program, it states that Toyota is aware of "certain internal malfunctions of the Brake Booster Assembly"!