Toyota Prius C1391 Error Code – Causes and Fixes
The C1391 error code is a common issue in Toyota Prius models across different generations, as well as other Toyota and Lexus hybrids. This code indicates an abnormal leak in the brake actuator, which can lead to braking performance issues and safety concerns. Addressing this problem promptly is crucial to maintaining the vehicle’s braking system.
Causes of C1391 in Toyota and Lexus Hybrids
The C1391 error typically stems from a failing brake master cylinder or brake booster accumulator. These components are responsible for maintaining brake pressure and ensuring smooth braking operation. Over time, internal seals can degrade, leading to pressure loss and triggering the C1391 code.
Signs of this issue include:
✅ Brake Warning Lights – ABS, traction control, and brake system lights may illuminate.
✅ Spongy or Weak Brakes – The brake pedal may feel soft or require more effort to stop.
✅ Unusual Noises – Hissing or buzzing sounds from the brake actuator are common indicators.
✅ Intermittent Brake Failure – In some cases, braking performance may fluctuate, creating an unsafe driving condition.
Fixing the C1391 Error Code
To resolve this issue, we replace the faulty brake master cylinder and brake booster accumulator with original Toyota parts. After installation, we perform a full system calibration to ensure proper brake operation and restore the vehicle’s safety features.
Toyota has acknowledged this issue in certain models and has provided an extended warranty on select vehicles to cover the repair. If you experience these symptoms, it’s best to have your vehicle inspected and serviced promptly. We recommend contacting Toyota directly to check if your vehicle is covered under the extended warranty.
