P25F3
Turbocharger/Supercharger Boost Sensor C Circuit Range/Performance
The third boost pressure sensor reading is implausible compared with manifold pressure or commanded boost. Either drift, leak in the sensing line, or contamination on the sensor diaphragm.
- 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 drift after thermal agingPossible
- Sensing hose blocked by oil residuePossible
- Sensor element aged beyond calibration windowLess likely
Parts involved
- Boost Pressure Sensor C
- Sensing Line
P25F3 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.