Powertrain
generic / SAE
P21F6
Fuel Control System B Too Lean Off Idle (Bank 2)
The secondary fuel control loop B on bank 2 reports a lean condition outside idle. On dual-injection systems (port + direct) the secondary loop trims port injection independently from the main loop.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number1 / F6
Possible causes
- Vacuum leak or injector clog high
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 80–1000 €
- Estimated time: 0.7–4 h
- Component: fuel injector
- Component: oxygen sensor
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012