P25F6
AIR System B
A general fault in the second secondary air injection (AIR) circuit. Detected by the O2 sensors which expect a lean swing during cold-start AIR pump operation but do not see one.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Failed AIR pump motor or impellerCommon
- Check valve seized by exhaust sootPossible
- Corroded or cracked air injection pipePossible
Parts involved
- Air Pump B
- Air Check Valve
- Air Pipes
P25F6 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.