OBD-II code · Powertrain (generic, extended)
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.
Is it safe to drive with P21F6?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyVacuum leak or injector clog
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.7–4 h
- Emissions test
- Likely to fail
- Parts involved
- Fuel Injector, Oxygen Sensor
Related codes
- P21F4Fuel Control System B Too Lean Off Idle (Bank 1)
- P21F3Cylinder 12 Injector B Circuit High
- P21F5Fuel Control System B Too Rich Off Idle (Bank 1)
- P21F7Fuel Control System B Too Rich Off Idle (Bank 2)
- P21F8Fuel Control System B Too Lean at Idle (Bank 1)
- P21F9Fuel Control System B Too Rich at Idle (Bank 1)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.