What it means
The ECM detects a range/performance 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 changes high-voltage battery power into low-voltage power for the vehicle’s 12-volt system. The control module monitors current sensor B to judge converter current; this code sets when the sensor’s reading is outside the expected range or does not track as expected, so it cannot be trusted for control.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
Symptoms
- Hybrid or EV system warning light
- Reduced power or limited electric drive
- Charging may be limited
- Reduced electric range
How to diagnose it
- Record freeze-frame data and check live data for DC/DC converter current sensor B; note whether the reading is implausible or fails to follow changes in converter operation.
- Check for related hybrid or charging-system codes that could point to a shared power, ground, or converter problem.
- With the vehicle powered down according to the manufacturer’s safety procedure, inspect sensor B’s mounting and its connector and wiring for displacement, damage, moisture, or corrosion.
- Check that the sensor is seated correctly and that its wiring and connector terminals are secure before considering sensor drift or aging.
- Have sensor B’s output and circuit checked against the manufacturer’s diagnostic procedure and specification; replace the sensor if its output remains out of range with sound wiring.
Common fixes
- Reseat and secure the sensor B connector if it is loose.
- Repair damaged wiring or corroded connector terminals in the sensor B circuit.
- Correct sensor B’s mounting if it has shifted.
- Replace current sensor B if its output is out of range despite correct mounting and wiring.
Can I keep driving?
Limit driving if the vehicle has reduced power or restricted electric drive, and avoid trips that depend on reliable hybrid operation. The inaccurate current reading may cause charging or electric-range limits; stop safely if a hybrid system warning escalates or the vehicle’s power drops sharply.
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.