P25C8
Brake Booster Temperature Sensor A Circuit Intermittent/Erratic
The booster temperature signal jumps or drops out for short moments. Usually a loose connector or a chafed wire that opens during vibration or thermal expansion.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Common causes
Ordered by how often each turns out to be the cause.
- Sensor connector not fully seated or pin tension lostCommon
- Harness chafed against booster housing or pedal bracketPossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Electric Brake Booster
- Temperature Sensor
- Wiring Harness
P25C8 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.