What it means
The BMS detects a circuit intermittent/erratic fault on voltage sense channel H of the high-voltage battery. Cell-group voltage measurement is unreliable on this channel.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The battery management system monitors voltage-sense channel H to measure a high-voltage battery cell group. This code sets when that signal becomes intermittent or erratic, so the BMS cannot maintain a dependable reading for the group.
Common causes
Most likely first.
- Loose or damaged voltage-sense connector
- Intermittent open or short in voltage-sense wiring
- Intermittent fault in the battery voltage-sensing circuitry
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and review live channel H voltage for dropouts or sudden changes, especially alongside neighbouring cell-group readings.
- With the vehicle powered down as directed by the manufacturer, inspect the channel H connector for a loose fit, corrosion, damaged pins, or signs of movement.
- Have the high-voltage battery isolated before touching sense connections, following the manufacturer’s safety procedure.
- Check channel H wiring for an intermittent open or short, using the wiring diagram and manufacturer’s specified test method.
- If the harness and connector remain stable, investigate the battery sensing circuitry for an intermittent channel H fault.
Common fixes
- Reseat and secure the loose channel H connector.
- Repair corroded terminals or damaged connector components.
- Repair chafed wiring or an intermittent open or short in the channel H sense path.
- Repair or replace faulty battery voltage-sensing circuitry if the connection and wiring are sound.
Can I keep driving?
The warning and power limits may come and go, but the BMS can still restrict propulsion or charging when the channel H signal drops out. Avoid long trips and stop safely if power becomes unpredictable.
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.