What it means
The control module detects an air-fuel ratio imbalance associated with system B on bank 1. The code does not specify a particular fuel-system layout or identify the cause of the imbalance.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The control module evaluates mixture feedback for system B on bank 1 and detects an air-fuel imbalance there. The label identifies bank 1 and system B, but the code does not establish the vehicle's fuel-system layout or name a failed part.
Common causes
Most likely first.
- System B fuel delivery fault
- Air or fuel imbalance on bank 1
- Sensor or wiring fault affecting mixture feedback
Symptoms
- Check-engine light on
- Rough running or hesitation
- Reduced power
- Increased fuel consumption
How to diagnose it
- Record freeze-frame data and compare bank 1 mixture feedback with bank 2 and other available system B data to see when the imbalance appears.
- Inspect system B fuel-delivery components and their wiring on bank 1 for damage, loose connections, or leaks.
- Check bank 1 for intake or exhaust leaks that could distort mixture feedback.
- Review the relevant sensor readings for system B and bank 1 for implausible or inconsistent values.
- Test system B fuel delivery and the associated sensors and circuits against the manufacturer's specification before replacing parts.
Common fixes
- Repair a confirmed air leak affecting bank 1.
- Clean or secure corroded or loose connectors in the system B fuel or feedback circuits.
- Repair damaged wiring or a confirmed sensor circuit fault affecting bank 1 mixture feedback.
- Repair or replace the system B fuel-delivery component on bank 1 if testing confirms its fault.
Can I keep driving?
If the engine runs normally and the warning light is steady, short, gentle trips are generally reasonable while arranging diagnosis. Avoid hard acceleration; stop if it runs severely rough, loses substantial power, or the warning light flashes.
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.