P21FA
Fuel Control System B Too Lean at Idle (Bank 2)
Secondary fuel control loop B reports a lean condition at idle on bank 2. Idle is sensitive to vacuum leaks since manifold flow is low.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Common causes
Ordered by how often each turns out to be the cause.
- Vacuum leak on bank 2 intakeCommon
Parts involved
- Fuel Injector
P21FA 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.