What it means
The BMS detects a circuit low fault on voltage sense channel I 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 reads a high-voltage battery cell group through voltage-sense channel I. This code sets when the channel I signal falls below the expected level, making that group’s voltage measurement unreliable.
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 compare channel I live voltage with neighbouring cell groups to verify the low signal and its operating conditions.
- With the vehicle powered down as specified by the manufacturer, inspect the channel I connector and wiring for a loose fit, corrosion, damaged insulation, or pin damage.
- Have the high-voltage battery isolated under the manufacturer’s safety procedure before handling sense wiring.
- Test channel I for a short to ground, an open, or excessive resistance using the manufacturer’s wiring diagram and specifications.
- If wiring tests pass, check the channel I battery sensing input and related control circuitry.
Common fixes
- Reconnect and secure a loose channel I connector.
- Repair channel I wiring shorted to ground or damaged insulation.
- Repair an open or high-resistance connection in the channel I sense circuit.
- Repair or replace faulty battery sensing circuitry if the wiring is intact.
Can I keep driving?
Avoid long trips because the vehicle may reduce power or restrict charging when it cannot trust the channel I cell-group voltage. Stop safely if power drops unexpectedly 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.