What it means
The ECM detects a high 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 converts high-voltage battery power to low-voltage power for the 12-volt system. The control module monitors current sensor B’s signal; this code sets when the signal is higher than expected, so the module cannot rely on it to regulate or assess converter current.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Hybrid or EV system warning light
- Reduced power or limited electric drive
- Charging may be limited
- Reduced electric range
How to diagnose it
- Save freeze-frame data and inspect live data for current sensor B to verify the high reading and whether it is constant or operating-dependent.
- Check for related hybrid-system or converter codes that may identify a broader power-supply or circuit issue.
- With the vehicle safely powered down according to the manufacturer’s procedure, inspect sensor B’s signal wire for damage or contact with a B+ supply wire.
- Inspect the sensor B connector for a loose fit, corrosion, moisture, or damaged terminals that could interrupt the circuit.
- Test for a short to B+ and check for an open sensor or circuit using the manufacturer’s diagnostic procedure; replace the sensor if the circuit checks out but the signal remains high.
Common fixes
- Repair damaged wiring or connector terminals that allow the signal to contact B+.
- Restore a secure, clean connection at current sensor B.
- Replace current sensor B if it is open or continues to report high with sound wiring.
Can I keep driving?
If the vehicle has reduced power or limited electric drive, keep driving to a minimum and avoid demanding journeys. An unreliable high-current reading may cause charging limits or further restrictions in hybrid operation.
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.