Fuel Control System B Too Lean at Idle (Bank 1)
Secondary fuel control loop B reports a lean condition at idle on bank 1. Idle is sensitive to vacuum leaks since manifold flow is low.
Affected components
- Fuel injector
- Intake manifold
- Oxygen sensor
Common causes
- High likelihood: Vacuum leak — most visible at idle
Possible symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.