2012 Toyota Prius V service brakes problems

“2012 Toyota Prius v with 89,662 miles. Multiple brake warning lights illuminated, and the vehicle stored diagnostic trouble code C1391, “Abnormal Leak in Accumulator.” The brake booster/accumulator pump is also cycling about every 13 seconds, even when the brake pedal is not being applied. The vehicle and components are available for inspection. My safety concern is that this involves a critical braking-system component. When the warning lights are on, regenerative braking is disabled, and braking behavior changes. I am concerned that continued deterioration could reduce braking performance or result in loss of brake assist. The issue has not yet been formally diagnosed by a Toyota dealer. I scanned the vehicle with a diagnostic scan tool, which currently shows C1391. I also contacted my independent repair shop, which recommended that Toyota diagnose the vehicle because this code is associated with the brake booster/booster pump failure previously addressed by Toyota Customer Support Program 20TE07. The vehicle has not yet been inspected by Toyota, police, insurance, or another manufacturer representative. A Toyota corporate case has been opened and escalated.…”

“Brake actuator assembly failure on a vehicle with 99,818 miles. Whirring sound when braking followed by lighting of several brake alert lights on dash including PCS and ABS and others. The whirring noise has occured for several weeks, but the light indicators happened on 6/28/26. Toyota has an acknowledged Customer Support Program (20TE07) for this exact failure on this exact and Toyota declined to cover the repair. This vehicle is 14 years old but has well under 150k miles and Toyota will not honor claim though they clearly are aware of the safety hazard.”

“The ABS system has failed. All brake related warning lights have appeared on the dash board and the ABS no longer works. The car will brake for now, but the pedal is mushy. The issue was diagnosed by a dealer. The diagnosis from the dealer, based on diagnostic trouble codes they did not provide, is that brake fluid is leaking in the master cylinder and brake booster. The recommendation is to have both the master cylinder and booster replaced. This vehicle has 143,000 miles on it. No accidents have occurred as a result of the brakes yet but how long before the brakes ultimately fail is unknown.”

“ABS, brake, and traction control lights, all illuminated at once on the dashboard. Inspection found DTC C1391 indicating the accumulator is leaking or failing to hold pressure correctly. We are advised that the braking system performance will decline, eventually failing. An very expensive repair is required and Toyota apparently has a shortage of the parts required. We cannot drive the vehicle given the potential of braking failure and cannot get it repaired in a timely manner for lack of Toyota parts.”

“The power assist braking system failed while I was driving in the rain. I was approaching a stoplight and I had to push down a lot harder and farther than I typically have to in order to stop. Luckily I was not going that fast and there were no cars ahead of me, but I stopped beyond where I had intended at a busy intersection. No warning lamps or messages had been illuminated prior to this happening. After the failure, the Brake system, ABS, and SLIP indicator lights were on and remained on when the car was restarted. An independent service center used a scan tool and found code C1391 stored in memory, indicating that the brake booster is unable to hold pressure due to an internal leak. The vehicle has not yet been inspected by the manufacturer, police or insurance, but can be available upon request.”

“I bought this car over a week ago for a good price, performed fine until I’m driving it home on the interstate and some abs/brake lights came on the dash. I enter my city and notice the brakes aren’t performing as tight as they were during the test drive. A few days later I take it to a local dealership to get it looked at. The brake actuator and pump had gone bad, causing this issue. It cost almost $5,000 to fix there, I couldn’t afford it so I had to only pay the $185 for the diagnostic. It’s an on and off thing, sometimes the lights go away and it brakes as it should, but most of the time the lights are on and the brakes don’t work as they should. I fear one day the brakes may eventually give out on me and cause an accident. I am available for inspection.”