What it means
State of charge of battery B (typically auxiliary or hybrid battery) shows performance fault — does not behave according to charging model.
At a glance
- Usually lights the check-engine light
How it works
Battery B is a second battery, often used as an auxiliary or hybrid-system battery, and its state-of-charge estimate is tracked by the battery monitoring and charging system. This code indicates that battery B's charge behavior does not match the system's expected charging model, which can result from a worn battery, a charging or connection problem, or a monitoring fault.
Common causes
Most likely first.
- Battery B aged or losing capacity
- Battery B charging or connection problem
- Fault in the battery monitoring or charging system
Symptoms
- Battery or charging-system warning light may come on
- Reduced performance of systems powered by battery B
- Start-stop or hybrid functions may be unavailable, if equipped
How to diagnose it
- Record freeze-frame data and note any battery, charging-system, start-stop, or hybrid warnings present when the code set.
- Identify battery B from vehicle service information and inspect its terminals, connections, and visible cables for looseness, corrosion, or damage.
- Check the battery B state-of-charge and charging data with a scan tool, including related battery-monitoring or charging codes.
- Test battery B's condition and charging circuit using the manufacturer's procedure and specifications.
- If the battery and charging connections pass testing, diagnose the battery monitoring system and its wiring for inaccurate readings.
Common fixes
- Clean and tighten battery B connections if they are loose or corroded.
- Repair damaged charging or monitoring wiring for battery B.
- Replace battery B if it fails the manufacturer's battery condition test.
- Repair or replace a faulty battery monitoring or charging component identified by testing.
Can I keep driving?
The vehicle may remain driveable, but systems powered by battery B, including start-stop or hybrid functions where fitted, may be limited or unavailable. If a charging warning appears or the vehicle has trouble starting, avoid relying on it for a long trip and have the battery system checked.
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.