C057BBrake Booster Temperature Sensor B Circuit/Open
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C057B is defined for an interrupted circuit of booster temperature sensor B. No manufacturer publishes it; GM maps the faults of this channel to C0579 and C057A only. Temperature sensors of this kind are normally NTC thermistors placed near the motor or on the power stage and read through a voltage divider. If the thermistor or one of its wires opens, the divider node is pulled toward the excitation voltage, and a thermistor design guide advises placing diagnostic thresholds beyond the usable temperature range to catch that. Microchip points out that an NTC on a power module follows case and heatsink temperature rather than the chip junction. Because the sensor is usually inside the booster, an open circuit often means replacing the unit.
- What you may notice
- Brake system warning and service message
- Temperature B missing or at an extreme value on the scan tool
- Assist possibly limited to protect the motor
- Likely causes
- LikelyOpen wire or loose pin between thermistor and booster electronics
- PossibleCracked thermistor body or broken lead after thermal or mechanical stress
- RareFailed solder joint on the booster circuit board
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.