P25F7
AIR System B Incorrect Flow Detected
The second AIR system delivers measurably more or less air than expected. Often a partially blocked pipe, a worn pump, or a leak between pump and check valve.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Air pipe partially blocked by carbonCommon
- Worn pump impeller reduces flowPossible
- Leak between pump and check valvePossible
Parts involved
- Air Pump B
- Air Check Valve
- Air Flow Sensor
P25F7 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.