What it means
The battery charger A input voltage sensor B circuit signal is intermittent or erratic. The code does not identify the specific source of the signal irregularity.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery charger A uses input voltage sensor B to report an electrical condition at the charger input to the control module. P0EFB sets when sensor B's signal is unstable or intermittent rather than consistently too low or too high, so the module receives an unreliable input.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Record freeze-frame data and review sensor B's live signal while charging to identify when it becomes erratic or drops out.
- With the vehicle safely powered down according to the manufacturer's procedure, check that sensor B's connector is fully seated and its lock is secure.
- Inspect sensor B's wiring and connector for damage, corrosion, or signs of movement that could cause contact to break under vibration.
- Check sensor B's ground/reference connection and circuit continuity for an unstable ground or intermittent open.
- If the circuit remains sound, test sensor B while gently checking its connector and harness for signal changes using the manufacturer's procedure.
Common fixes
- Reseat and secure sensor B's connector.
- Clean corroded connector contacts and restore firm pin contact.
- Repair loose or damaged wiring causing an intermittent connection.
- Restore a noisy or poor ground/reference connection.
- Replace sensor B if its output remains erratic with a stable circuit.
Can I keep driving?
Charging may start and stop unpredictably or proceed slowly, and charging functions may be limited. Avoid depending on the charger until the intermittent fault is found, and follow the vehicle's charging warnings.
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.