2012 Toyota Prius v

The contact owns a 2012 Toyota Prius. The contact stated that while driving 65 MPH and depressing the brake pedal there was a buzzing sound coming from the vehicle and the brake warning light illuminated. The contact stated that after inspecting the vehicle, the brake fluid level was very low. The vehicle was taken to a service center where it was diagnosed and DTC: C1391; was retrieved. The contact was informed that a leak in the brake accumulator had caused the brake master cylinder and hydraulic power brake accumulator to fail and needed to be replaced. The vehicle was scheduled to be repaired by the service center. The manufacturer was made aware of the failure via telephone. The contact stated that the manufacturer was aware of the failure and offered an extended warranty to cover the repair. However, the part needed to be replaced. The failure mileage was approximately 81,239.

The contact owns a 2012 Toyota Prius V. The contact stated that while driving 65 MPH, brake fluid was leaking from the vehicle. While driving over 45 MPH, the brake pedal became firm, requiring the driver to exert extra force while depressing the brake pedal; the brakes failed to respond as intended. Additionally, a burning and toxic odor was present during the failure. Multiple warning lights illuminated on the instrument cluster, including the ABS system, parking brake, brake malfunction, and electronic stability warning lights. In addition, the automotive brake system, brake pump, and pressure warning messages were displayed. The vehicle was taken to a local dealer, where it was diagnosed with a failed brake booster assembly after inspection. The dealer determined that the brake booster assembly needed to be replaced. The contact associated the failure with Customer Support Program: 20TE07. The contact was referred to the NHTSA Hotline by a lawyer, and the contact had found a class action lawsuit related to the failure. The failure mileage was approximately 187,000.

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. There were no known brake warning lights before this incident. The problem first became apparent when multiple brake warning lights illuminated. Afterward, I noticed the brake booster pump cycling unusually often. Toyota previously identified C1391 as a qualifying code under 20TE07 for certain 2012–2014 Prius v brake booster/booster pump failures. My vehicle is outside the time-based coverage period despite relatively low mileage. I am reporting this because I am concerned this safety-related failure may continue occurring in similarly aged vehicles.

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.

Driving down the highway, the engine suddenly threw a rod, causing a terrible jolt, after which the engine burst into flames. There had been no warning lights.

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 contact owns a 2012 Toyota Prius V. The contact stated that while driving at an undisclosed speed, the brake master cylinder was constantly cycling. No warning lights were illuminated. The vehicle was not taken to the dealer or an independent mechanic to be diagnosed or repaired. Most recently, while the vehicle was turned off, the brake master cylinder was cycling. The contact stated that while the keys were in his hands and standing several feet away from the vehicle, the brakes started cycling. The manufacturer was notified of the failure but offered no assistance. The approximate failure mileage was 140,000.

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.

The hybrid system fails to enter “Ready” mode with no SMR engagement audible from the junction box. Dashboard displays ABS, brake, engine, and master warning lights. OBD codes include U0142, U0155, and previously U0073 . Rear brake lights function normally when pedal is pressed. Dealer said to pay 250$ for diagnostic and diagnosed incorrect voltage from brake light switch and quoted $348.94 to replace, but refused to proceed with open safety recall J0V / 18V684 (NHTSA 18V684000) citing inability to achieve “Ready” mode. Recall covers inverter failure leading to loss of motive power. Dealer declined to jump 12V battery or use external power to perform required software update and inverter inspection. Vehicle remains inoperable and poses safety risk due to sudden power loss potential. Component (inverter G9200-47141) available for inspection. Problem confirmed by dealer diagnostics. No police or insurance inspection. Warning lamps appeared after 12V battery replacement three months ago.

While driving 60 mph in highway, ABS, traction control and brake lights lit up and vehicle lost its effective braking power. There were no prior warnings prior to this failure. It was a sudden incident. Since it wasn't rush hour, I could safely reduce speed and bring the car to stop. Situation could have been much different if it was normal hours. After taking the car to dealership, it indicated DTC code 1391, Brake Assembly Failure. The car was fixed at dealership at cost of $3,000. When researched further, it appeared that there is broader pattern of failures. Numerous reports have been made by owners of 2010–2015 Toyota Prius, Prius PHV, 2012–2015 Prius V, 2012–2014 Camry Hybrid, and 2013–2015 Avalon Hybrid vehicles, all of which share the same brake booster pump assembly design manufactured by Advics Co., Ltd. Dealerships, including Capistrano Toyota and Claremont Toyota in California, have previously petitioned NHTSA regarding this very defect. Their 2019 letter to the agency documented that Toyota: * Knowingly excluded hundreds of thousands of hybrids from prior safety recalls (DOH 13V-235 and KOL 19V-544) despite identical failures. *Issued “post-failure” repair programs (Warranty Enhancements ZJB, ZKK, ZKC, ZLM, 20LE03, 23TE06 and 23TE07) only after owners experienced brake failure. * Identified the same DTC codes (C1252, C1253, C1256, C1391, U0293) in both recalled and unrecalled vehicles—codes that correspond to accumulator leaks, loss of brake pressure, and failure of brake assist and stability control systems. * Admitted through Technical Service Bulletin TSB-0130-19 that these defects caused loss of hydraulic pressure, increased stopping distance, and total loss of brake assist in affected hybrids. In short, the defect pattern across multiple hybrid models is identical to those already recognized by Toyota and NHTSA under prior recall campaigns, but for reasons unexplained, Toyota limited the recall population and left many consumers unprotected

After 13 years and 112,000 the brake booster and brake booster pump went out on my car. Toyota extended the warranty to 10 years because of this issue. Now just outside of the 10 yr mark my car has this issue and Toyota will not cover it. This is a huge expense and also a major issue with this year and model of car.

I have a Prius v 2012, and the lights for abs turned on and when I checked on internet Toyota was repairing the part for 150k miles and 10 years but this is a safety feature my car is now at 149922, And while I was on road suddenly the signs came up and I the brakes were hard, and this is a problem for my safety and for others too since It doesn’t brake well

Brake getting stuck on the floor would have to press on brake really hard just to get a response, this will happen out of the blue! Driving in highway or just driving off the driveway. I almost hit a car in front of me due to lack of brake, i had to swerve to the side! First appear 1 day after buying the car..This issue needs to be worked on right away.

While driving on the freeway I applied the brakes and the brakes suddenly felt soft and not very responsive. At that moment 3 dashboard lights turned on: ABS, BRAKE, and the slip indicator lights. I carefully got out of the freeway, parked the car, and had the car towed to an independent mechanic. The mechanic detected brake booster and actuator problems, code C1391.

While driving on the interstate I went to slow down to merge and my brakes failed. The following warning lights came on: Master Warning Light (yellow), Brake System Warning Light, Brake System warning light (red), ABS Warning Light, and the Slip Indicator light. My vehicle was towed to a Toyota Dealership and after running a diagnostic test, they confirmed that it was the "Break booster with accumulator c1391 stored internal leak of accumulator and need immediate attention" which they quoted at $4,295.68 to fix. After researching the issue saw A Customer Support Program 20TE07 was issued taking responsibility for the faulty Brake Booster Pump Assembly however only covered the repair for a two-year period and only if it was one of the identified diagnostic trouble codes listed in the CSP issued by Toyota but expired in Feb 2022. The code pulled from my vehicle 3 days ago was listed in this document, but the coverage only covers until Feb 2022. This is not a normal wear and tear issue, it is a faulty part that Toyota identified as a life and death safety concern but refuses to do anything about because mine didn't show an issue within their 2-year CSP timeframe. Toyota identified that there are roughly 118,950 2012-2014 model year prius V with a production period of late September 2010 to mid-November 2014 vehicles that this faulty part affects along with everyone else on the road with these vehicles as it causes failure of the brake booster pump assembly, which leads to a loss of braking assist and the deactivation of the Vehicle Stability Control system. For the safety and lives of the owners of these vehicles and all of the other lives of the drivers on the road that this could affect in the case of this faulty part should there be a catastrophic accident, like mine could have been, a nationwide recall on this part MUST be issued.

C1391 - Abnormal Leak in Accumulator

CA No problem

My Prius, along with the thousands of others this has apparently happened to according to a quick online search, has had the C1391 code appear, indicating a failed brake actuator and accumulator. It, like the thousands of Priuses from this generation, have had these faulty brake pump systems develop a leak and begin to fail. You will hear a whirring and hissing noise constantly when it starts going out, eventually resulting in a Christmas tree of dash warning lights and reduced braking due to a failsafe kicking on. Toyota apparently issued a "customer service bulletin" that is now ineffective as it only covered if you had the system fail within 10 years of manufactor or 150,000 miles AND had the codes appear. Most people's Priuses go out AFTER this, unless you're driving it like you stole it. It is a hefty repair too, being quoted at over $3000 at the Toyota STEALSRSHIP!! I have since gone to an independent mechanic and had one portion replaced in hopes that would fix the issue, but it turns out both the actuator and accumulator are needed to be replaced, which is extremely expensive, more so for the actuator than the accumulator, but still exorbitantly expensive. In conjunction with this, Toyota further added difficulties by making their paet numbers they have listed different from the mark number engraved on the part, so buying third party is made a bigger hassle by this as they will not know for certain the part number. This is a huge safety concern as this affects the vehicle's ability to brake. Their service bulletin was the equivalent of offering people bandaids years before they'd be anywhere to getting a cut!! Please investigate and please please PLEASE lead to Toyota issuing an actual recall, regardless of miles or year from manufacture. More and more Priuses are reaching the time where this will occur and it's a huge safety concern, if not an environmental concern when people start disposing of Priuses due to this massive failure with hefty repair bills.