P25C4 code meaning
Brake Booster Temperature Sensor A Circuit
Powertrain system Generic code P25xx codes Check engine light
What P25C4 means
P25C4 covers the first temperature sensor of an electromechanical brake booster, in which an electric motor and gear set take the place of the vacuum diaphragm, as in Bosch's iBooster. The booster electronics use this value to protect motor and control unit from overheating during long or repeated braking. P25C4 reports an unusable sensor circuit without a direction. GM's 2023 Corvette Z06 table 23OBDG07 lists only the separate low and high codes P25C6 and P25C7 for this sensor in its EBCM section, plus C0579 and C057A for a second sensor; a generic circuit code does not appear there, and no manufacturer publishes P25C4. GM requires the booster temperature sensors to be fault free before it runs its rotor and ECU over-temperature checks, so a failed sensor removes that protection.
P25C4 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P25C4
- Brake system warning in the cluster
- Brake pedal may feel harder if assistance is reduced
- Stored code, often together with chassis codes
Common causes of P25C4
- Most likelyTemperature sensor inside the booster unit defective
- PossibleCorroded or loose booster connector
- Less likelyFault in the booster control electronics
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Electric brake boosterTemperature sensorWiring harness
What each part of P25C4 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| C4 | The exact fault in that area. |
What to do next
- Note P25C4 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 P25C4
What does P25C4 mean?
P25C4 means "Brake Booster Temperature Sensor A Circuit". P25C4 covers the first temperature sensor of an electromechanical brake booster, in which an electric motor and gear set take the place of the vacuum diaphragm, as in Bosch's iBooster. It is a generic code, so it means the same on every make.
Is it safe to drive with P25C4?
Drive gently and only to a workshop. With P25C4 the car can go into limp mode (reduced power) to protect itself.
Will P25C4 fail an emissions test?
P25C4 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 P25C4 to fix?
Difficulty: workshop only. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P25C4 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.