P25F7AIR System B Incorrect Flow Detected
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- With P25F7 the engine controller finds that the air delivered by secondary air system B does not match its expectation while the system is switched on after a cold start. Depending on the design, it judges the flow from how the oxygen sensors on that side react, from a pressure sensor in the air line or from pump behaviour. For 2006 and later vehicles outside LEV III, CARB demands detection before reduced flow pushes emissions beyond one and a half times the relevant FTP limit; LEV III vehicles use the threshold table instead, and with separate paths each bank counts on its own. No manufacturer documents P25F7 publicly. On Toyota's 2UZ-FE V8, a bulletin blames debris passing through the pump and fouling the valves for comparable faults. P0411 is the matching code for system A, P25F6 the general fault of system B.
- What you may notice
- MIL on after one or two cold starts
- Emissions test failed or readiness incomplete
- Driveability normally unchanged
- Likely causes
- LikelyAir pump of system B delivers too little air
- PossibleSwitching or check valve fouled or stuck partly closed
- PossibleAir passages to the exhaust restricted by carbon deposits
- RareLeaking air hose so that part of the flow escapes
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €80 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.