What it means
The ECM detects a intermittent/erratic fault on the dc/dc converter voltage sensor b. 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 lower-voltage power for the vehicle’s electrical system. The control module monitors voltage sensor B for a steady, plausible signal; this code sets when that signal becomes erratic or drops in and out, so it cannot be relied on for control.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Hybrid/EV system warning light may turn on
- Reduced power or charging performance
How to diagnose it
- Record freeze-frame data and check live readings for DC/DC converter voltage sensor B to see when the signal becomes unstable.
- Inspect sensor B’s connector for incomplete seating, corrosion, damaged seals, or loose pins.
- Check the sensor B wiring and ground reference for chafing, poor connections, or damage that could cause an intermittent signal.
- With the vehicle secured and following the manufacturer’s high-voltage precautions, monitor the sensor reading while gently moving the accessible low-voltage harness to look for dropouts.
- Test sensor B’s circuit and ground continuity against the manufacturer’s specification, then assess the sensor or converter only if the wiring checks out.
Common fixes
- Reseat and secure the DC/DC converter voltage sensor B connector.
- Repair damaged wiring or corroded or loose connector terminals in the sensor B circuit.
- Repair a poor ground reference affecting the sensor B reading.
- Replace the faulty voltage sensor B or service the converter if testing confirms an internal fault.
Can I keep driving?
Avoid relying on the vehicle for normal driving if power is reduced or the hybrid/EV warning is on; the converter reading may be unreliable and the vehicle may limit power. Arrange prompt diagnosis, and stop safely if the vehicle loses power or displays a high-voltage system 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.