What it means
The BMS detects a circuit low 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 uses voltage-sense channel H to read the voltage of a high-voltage battery cell group. This code sets when the channel signal is lower than the BMS expects, so it cannot rely on that group’s voltage reading.
Common causes
Most likely first.
- Short to ground in voltage-sense wiring
- Open or high resistance in voltage-sense wiring
- Loose, damaged, or corroded connector
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
- Record freeze-frame data and scan live cell-group voltages to see whether channel H is implausibly low or differs from neighbouring groups.
- With the vehicle powered down as specified by the manufacturer, inspect the channel H sense connector and accessible wiring for looseness, corrosion, pin damage, or chafing.
- Have the high-voltage battery isolated using the manufacturer’s safety procedure before handling any battery sense connections.
- Test channel H wiring for a short to ground, an open, or excessive resistance using the manufacturer’s wiring diagram and specifications.
- If the wiring and connections pass, compare the channel H input at the battery monitoring circuitry with the other channels to identify a possible sensing-circuit fault.
Common fixes
- Reconnect and secure a loose channel H connector.
- Repair damaged channel H wiring or insulation causing a short to ground.
- Repair an open or high-resistance connection in the channel H sense path.
- Repair or replace faulty battery voltage-sensing circuitry if wiring tests pass.
Can I keep driving?
Avoid relying on electric power or attempting long trips; the vehicle may limit power or refuse to charge because it cannot verify the channel H cell-group voltage. If power is reduced or the warning escalates, stop somewhere safe and arrange service.
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.