P21FF
Fuel Control System B Too Rich at Higher Load (Bank 2)
The secondary fuel control loop B reports a rich condition at higher load on bank 2. Rich at high load typically points to a stuck-closed return on the fuel pressure regulator or over-delivering injectors.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Black smoke from exhaust on acceleration
- Smell of unburned fuel, fouled spark plugs
Common causes
Ordered by how often each turns out to be the cause.
- Injectors over-deliver on bank 2Common
Parts involved
- Fuel Injector
P21FF 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.