2012 TOYOTA PRIUS C — Problems, Recalls & Safety Data

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.

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.

I own a 2012 Toyota Prius C with approximately 156,578 miles. The vehicle has been diagnosed with C1391 – Abnormal Leak in Accumulator, which causes the brake actuator to lose hydraulic pressure. This results in frequent buzzing from the actuator pump, illuminated warning lights (BRAKE, ABS, Traction Control), and loss of ABS and stability control. The condition increases stopping distance and creates a serious safety hazard. Toyota previously acknowledged this exact defect under Customer Support Program CSP 21TE01, which covered brake booster and pump assemblies for certain Prius and Prius C models when codes such as C1391 were present. However, the program expired on November 30, 2022, and my vehicle is just over the 150,000-mile coverage limit. Despite this, my Prius exhibits the same defect that Toyota has already recognized as a safety-related issue. Toyota Carlsbad confirmed the diagnosis and quoted $3,399.55 plus tax for repair, with a reduced courtesy estimate of $2,817.86 plus tax, but declined goodwill assistance since CSP 21TE01 expired. Given the widespread reports of brake actuator failures in Prius models, I believe this represents a systemic safety issue that warrants NHTSA investigation and potential recall/extended coverage.

Brake Actuator and ABS Accumalator failed. It is a common failure reported by multiple owners on these cars. I was on the high way going 70 when it failed and lost any brake boost I had putting me in a very dangerous situation where I narrowly avoided an accident. Upon scanning the car's codes I got code C1391 which I looked up and saw a bunch of other people who were also struggling with this issue.