C057C Brake Booster Temperature Sensor B Circuit Range/Performance

C057C covers a temperature B value that is electrically valid but behaves implausibly – it stays frozen, climbs too slowly after hard use, or departs from what the module's thermal estimate predicts. No manufacturer documents this code publicly. In Hitachi Astemo's electric booster patent the measured motor and drive circuit temperatures decide when current and thus assist are limited and when they are restored, with an intermediate step if the pedal is still pressed; a wrong but believable value would therefore throttle assist too early or let the motor run too hot. Thermistor makers name moisture, cracking, solder stress and resistance drift as typical long-term failures. The module may restrict assist as a precaution.

Likely causes

Symptoms

• Brake warning, often after long or repeated braking
• Temperature B frozen or lagging behind temperature A
• Assist reduced earlier than usual

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: patents.google.com, analogtechnologies.com, ww1.microchip.com.