What it means
The BMS detects a circuit 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 BMS measures a cell group in the high-voltage battery through voltage sense channel H. This code identifies a fault in the channel H circuit, leaving that cell-group voltage reading unreliable.
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
- Save freeze-frame and BMS data, compare channel H's reading with nearby cell groups, and note any related battery codes.
- Check the manufacturer's high-voltage isolation procedure before inspecting battery sense wiring or connectors.
- With the battery isolated as specified, inspect channel H connectors and accessible wiring for looseness, corrosion, pin damage, an open, or a short.
- Test channel H for continuity, shorts, and excessive resistance using the manufacturer's procedure and specification.
- If the wiring passes, use the manufacturer's diagnostic procedure to assess the channel H sensing input and BMS circuitry.
Common fixes
- Reseat a loose channel H connector using the specified isolation procedure.
- Clean or repair corroded or damaged channel H terminals.
- Repair or replace channel H wiring with an open, short, or high-resistance fault.
- Repair or replace the battery sensing or BMS circuitry if tests confirm an internal fault.
Can I keep driving?
Reduced power, limp mode, or charging problems may mean the BMS is restricting battery use because channel H's reading is unreliable. Avoid relying on normal electric range and arrange prompt diagnosis; stop if the vehicle becomes unsafe to drive.
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.