What it means
Fuel control system B on bank 2 has detected a lean condition off idle. The code identifies the operating condition and fuel control system; it does not specify a particular injection type or cause.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Fuel control system B adjusts fueling for bank 2 using air-fuel and oxygen sensor feedback. This code sets when the system detects a lean mixture in bank 2 while the engine is off idle, which can result from extra air, restricted fuel delivery, or inaccurate feedback in that operating range.
Common causes
Most likely first.
- Intake or vacuum leak
- Restricted or dirty fuel injector
- Low fuel pressure
- Faulty air-fuel ratio or oxygen sensor
- Exhaust leak ahead of the sensor
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
How to diagnose it
- Save freeze-frame data and review bank 2 fuel trims and sensor readings at the off-idle speed and load where the code appeared.
- Inspect bank 2 intake runners, vacuum connections, and exhaust joints ahead of its sensor for leaks that could skew the mixture or feedback.
- Compare bank 2 fuel trims with bank 1 during a controlled off-idle check to see whether the lean reading is bank-specific.
- Check fuel pressure and delivery under the manufacturer's specified test conditions to rule out supply that falls short as demand increases.
- If there are no leaks or supply problems, test bank 2 injectors for restriction and verify air-fuel or oxygen sensor response and wiring.
Common fixes
- Repair an intake or vacuum leak affecting bank 2.
- Repair an exhaust leak ahead of the bank 2 sensor if it is drawing in air.
- Clean or replace a restricted bank 2 injector when testing confirms poor fuel delivery.
- Repair low fuel supply or replace a faulty sensor only after confirming it fails the manufacturer's tests.
Can I keep driving?
Short, gentle driving may be possible if the engine is stable, but avoid heavy acceleration and loads. A sustained lean condition can cause misfires or excessive heat; stop if the engine stalls, runs very roughly, or loses substantial power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.