C057E code meaning
Brake Booster Temperature Sensor A/B Correlation
What C057E means
With two temperature sensors in the booster the module can cross-check them: after a long rest both should be close to ambient, and under load they should move in a consistent pattern. C057E is set when sensors A and B disagree beyond a plausible margin. GM fits two such channels in its booster (A: P25C6/P25C7, B: C0579/C057A), but its public tables do not list C057E, and no other maker documents it either. The idea is known from related systems: Safran compares redundant temperature sensors in electric brake actuators and discards inconsistent ones, and Hitachi Astemo's electric booster carries separate motor and drive circuit sensors. As the module cannot tell which reading is wrong, it usually protects the motor by reducing assist.
C057E 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 C057E
- Brake system warning with service message
- Temperatures A and B clearly apart on the scan tool after a cold start
- Reduced brake assist
Common causes of C057E
- Most likelyOne of the two thermistors drifted or lost thermal contact
- PossibleAdded resistance in one sensor circuit, e.g. corroded contact
- Less likelyReal local overheating of motor or power stage, e.g. after jammed mechanics
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 C057E means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7E | The exact fault in that area. |
What to do next
- Note C057E 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 C057E
What does C057E mean?
C057E means "Brake Booster Temperature Sensor A/B Correlation". With two temperature sensors in the booster the module can cross-check them: after a long rest both should be close to ambient, and under load they should move in a consistent pattern. It is a generic code, so it means the same on every make.
Is it safe to drive with C057E?
Drive gently and only to a workshop. With C057E the car can go into limp mode (reduced power) to protect itself.
Will C057E fail an emissions test?
C057E 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 C057E to fix?
Difficulty: hard. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will C057E 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.