OBD-II code · Powertrain (generic, extended)
P21FB Fuel Control System B Too Rich at Idle (Bank 2)
The secondary fuel control loop B reports a rich condition at idle on bank 2. Idle rich often means injectors that leak at low duty cycle.
Is it safe to drive with P21FB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyInjectors leak on bank 2
Symptoms
- Check engine light on
- Increased fuel consumption
- Black smoke from exhaust on acceleration
- Smell of unburned fuel, fouled spark plugs
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
Related codes
- P21F9Fuel Control System B Too Rich at Idle (Bank 1)
- P21F8Fuel Control System B Too Lean at Idle (Bank 1)
- P21FAFuel Control System B Too Lean at Idle (Bank 2)
- P21FCFuel Control System B Too Lean at Higher Load (Bank 1)
- P21FDFuel Control System B Too Rich at Higher Load (Bank 1)
- P21FEFuel Control System B Too Lean at Higher Load (Bank 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.