2011 TOYOTA PRIUS Complaints

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known issue of Toyota for my vehicle and that Toyota extended a warranty years ago; however, the extended warranty is no longer valid for this known defect.

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.

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)

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.

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.

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.