Brake booster abnormally long

The "brake booster abnormally long" issue in 2009-2015 Toyota Prius models often relates to diagnostic codes like C1252 (Brake Booster Pump Motor On Time Abnormally Long) or C1256 (Accumulator Low Pressure). This problem affects the electronically controlled brake system, which includes the brake booster, master cylinder, and ABS pump/accumulator. Common symptoms include warning lights (ABS, Brake, Traction Control, or "Braking Power Low"), pulsating brake pedals, reduced braking power, or a chattering/honking noise from the pump, especially when the car is off.

The issue stems from internal leaks in the brake booster or master cylinder, faulty pump/accumulator, or worn O-rings, causing pressure loss. It’s a frequent problem in these Prius models, particularly at higher mileage (120,000–240,000 miles). Toyota’s Customer Support Program (ZJB) extended warranty coverage to 10 years or 150,000 miles for specific codes like C1391, but many owners face failures just outside this period, with repair costs of $2,000–$4,000 at dealerships.

Safety risks are significant, as reduced braking power can increase stopping distances or cause sliding, especially on slick surfaces. NHTSA investigations and a 2020 petition for a recall of ~1 million vehicles highlight the issue’s severity, though no comprehensive recall exists. Some owners opt for DIY repairs ($600–$1,500 for parts) using YouTube tutorials, but this is complex and requires diagnostic tools for brake bleeding. Used parts ($100–$150) or replacing ABS sensors (~$30) can be cheaper alternatives, though less reliable. Independent shops may charge ~$2,500 versus $4,000 at dealers.