What it means
The BMS detects a circuit 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
Voltage-sense channel I carries the high-voltage battery cell-group measurement to the battery management system. This code indicates a fault in the channel I circuit, leaving the BMS unable to rely on that group’s voltage reading.
Common causes
Most likely first.
- Open or short in voltage-sense wiring
- Loose, damaged, or corroded connector
- Fault in the battery voltage-sensing or control 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
- Record freeze-frame data and compare channel I live voltage with neighbouring groups to establish whether it is missing, unstable, or implausible.
- With the vehicle powered down as specified by the manufacturer, inspect the channel I connector and accessible wiring for looseness, corrosion, broken pins, or damage.
- Have the high-voltage battery isolated under the manufacturer’s safety procedure before handling battery sense connections.
- Use the wiring diagram to test channel I for an open or short and check connector continuity against the manufacturer’s specifications.
- If the channel I harness passes, check the battery sensing or control circuitry for a fault at that input.
Common fixes
- Reconnect and secure a loose channel I connector.
- Repair damaged, open, or shorted channel I wiring.
- Replace corroded or damaged channel I connector terminals.
- Repair or replace faulty battery voltage-sensing or control circuitry if the circuit checks pass.
Can I keep driving?
The vehicle may limit power or slow or stop charging because the BMS cannot verify the channel I cell-group voltage. Keep any necessary trip short and avoid relying on electric range until the fault is repaired.
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.