P23FF
Bank 2 System B Air-Fuel Ratio Imbalance
The secondary fuel system B on bank 2 (e.g. port-injection rail in a dual-injection engine, or LPG/CNG rail in a bi-fuel system) does not maintain calibrated mixture - lambda response on bank 2 is biased by an offset on the B system.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Secondary fuel system has driftedCommon
Parts involved
- Fuel System B B2
P23FF 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.