C057C code meaning
Brake Booster Temperature Sensor B Circuit Range/Performance
What C057C means
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.
C057C at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of C057C
- Brake warning, often after long or repeated braking
- Temperature B frozen or lagging behind temperature A
- Assist reduced earlier than usual
Common causes of C057C
- Most likelyThermistor resistance drifted through age, moisture or heat cycling
- PossibleSensor lost thermal contact with motor or power stage
- Less likelyPlausibility model in the booster software too strict
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake booster temp sensor bElectric brake booster
What each part of C057C means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7C | The exact fault in that area. |
What to do next
- Note C057C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C057C
What does C057C mean?
C057C means "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. It is a generic code, so it means the same on every make.
Is it safe to drive with C057C?
Drive gently and only to a workshop. With C057C the car can go into limp mode (reduced power) to protect itself.
Will C057C fail an emissions test?
C057C is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C057C to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will C057C clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.