2012 TOYOTA PRIUS Complaints

While driving 65 mph on the expressway on January 12th, 2026 under cruise control, I tapped my brakes to slow down. My brake warning light came on, along with the ABS warning light, and the anti-swerve warning light. Cruise control no longer worked, and my brakes were noticeably hard to apply. I immediately had the vehicle computer checked and the issue is a leaking brake booster component, a faulty part known by Toyota to fail prematurely with this and other Prius models. No recall was issued however. The car is now unsafe to drive until a ~$4000 repair is done, according to my service representative.

Brakes went soft with little braking power. Traced the fault code to a faulty braking actuator; toyota says this is past the coverage date for the recall.

My 2012 Toyota Prius plug in hybrid had just passed state inspections and was even looked at by a dealership a year ago with no reported issues. I brought up a whirring issue at the dealership when breaking but the dealership said that’s normal for a hybrid. In a matter of minutes while driving, the traction light, brake light, and ABS light came on as well as a groaning, whirring sound when breaking. Over time, the breaks failed and I could not stop the car, almost causing a wreck because I could not stop without putting all my body weight on the break pedal. When taking it to the Toyota dealership for a whole diagnostic, they said it was a break actuator and break booster failure that is known to happen with Prius’s. They quoted me $3000 for a repair and then marked my breaks as yellow not red on their sheet implying I could still drive it despite the dangerous situation of driving without functioning breaks. When looking into it, this seems to be a known and common problem with Prius’s due to a faulty manufactured part. Codes were c1391, wc1256, and c1252. I believe this part should be recalled and Toyota should fix these faulty parts, especially considering they inspected my car and did not mention it as an issue despite it being a known issue. I got a second opinion from Mavis Tires and they concurred with the diagnosis but could not fix it.

While driving, the vehicle experienced a sudden brake system malfunction without prior warning or gradual degradation. The vehicle was being operated under normal driving, road, and weather conditions. No recent brake service, repairs, or aftermarket modifications had been performed prior to the failure. Multiple warning lights illuminated on the dashboard, including the ABS warning light, brake warning light, and traction control warning light. Shortly after the warning lights appeared, the vehicle began emitting continuous warning beeps. Audible buzzing or pumping noises were also present from the brake system during the malfunction. During this event, brake performance was reduced and braking felt inconsistent. The brake pedal became hard at times and spongy at other times, requiring increased effort to slow the vehicle and resulting in unpredictable braking response. This created a safety concern while the vehicle was in motion. The driver was forced to alter driving behavior and exercise extreme caution due to reduced braking confidence and unpredictable pedal feel. The malfunction has occurred intermittently during normal driving. The condition temporarily resolves on its own and later reoccurs without corrective action. The suspected failed component is the brake actuator / ABS actuator assembly. A diagnostic scan retrieved fault codes C1252 (Brake Booster Pump Motor ON Time Abnormally Long), C1253 (Pump Motor Relay Malfunction), and C1256 (Accumulator Low Pressure), which are consistent with brake actuator malfunction. The failure occurred at approximately 154,000 miles. This vehicle model and generation have a documented history of premature brake actuator failures with similar safety-related symptoms reported by other owners. The condition places the driver and others at risk due to unpredictable braking behavior, reduced braking effectiveness, and repeated warning alarms while driving. Warning lamps and audible alerts continue intermittently.

The contact owns a 2012 Toyota Prius. The contact stated that while reversing, the driver's side rear wheel flipped over. The vehicle was towed to the dealer, where it was diagnosed with a corroded I-Beam assembly on the rear wheel. The contact was informed that the driver's side rear hub and the BRG assembly, rear suspension, and bolts needed to be replaced. The vehicle was repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 196,347.

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.

Odometer Fraud. The contact’s son recently purchased a 2012 Toyota Prius. The vehicle was a private sale. After the purchase, it was discovered that there was a mileage discrepancy based on the Carfax report. At the time of purchase, the vehicle displayed 137,000 miles. However, the Carfax report listed the mileage as 281,586 miles, and the current mileage on the vehicle was 151,103.

While driving on a city road below the speed limit, braking was compromised leading to loss of traction and failure of the ABS system. During the incident, the brake, ABS, and engine warning lights all turned on and a collision was only avoided due to pumping of the brakes. Further investigation by a mechanic revealed a failure of the brake actuator system. Failure of this system has increased the stopping distance of the vehicle considerably and makes braking unreliable and unpredictable.

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.