What it means
The ECM detects a intermittent/erratic fault on the dc/dc converter current sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The DC/DC converter provides low-voltage power from the high-voltage system, and current sensor B reports converter current to the control module. This code sets when the sensor B signal is intermittent or erratic, such as when a poor connection or unstable ground makes the reading jump unpredictably.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Hybrid or EV system warning light
- Intermittent reduced power
- Charging may be interrupted
- Reduced electric range
How to diagnose it
- Record freeze-frame data and watch live data for current sensor B for sudden jumps or dropouts, especially when the warning appears.
- Check for related converter or hybrid-system codes and note whether the fault is associated with vibration or changing electrical load.
- With the vehicle powered down using the manufacturer’s safety procedure, check that sensor B’s connector is fully seated and its terminals are not loose or corroded.
- Inspect the sensor B wiring and ground reference for chafing, poor connections, or damage; gently move accessible wiring while monitoring data only if the manufacturer’s procedure permits it.
- Test the sensor B circuit and ground stability using the manufacturer’s diagnostic procedure, then replace the sensor only if its signal remains erratic with secure wiring and connections.
Common fixes
- Reseat and secure the current sensor B connector.
- Clean or repair loose or corroded terminals and restore a sound ground reference.
- Repair wiring damaged by rubbing, heat, or movement.
- Replace current sensor B if the signal remains erratic after the connector, wiring, and ground are corrected.
Can I keep driving?
Intermittent power reduction or charging interruptions can worsen without warning, so avoid long trips and heavy acceleration until the fault is diagnosed. Stop safely if power drops sharply or the hybrid system displays a more severe warning.
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.