What it means
The BMS detects a circuit high 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 reads a high-voltage battery cell group through voltage-sense channel H. This code sets when the channel H signal is higher than the BMS expects, making that group’s voltage measurement unreliable.
Common causes
Most likely first.
- Short to voltage 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 H live voltage with neighbouring cell groups to confirm the high reading and note when it occurs.
- With the vehicle powered down according to the manufacturer’s procedure, inspect the channel H connector and wiring for damage, corrosion, contamination, or contact with another powered circuit.
- Have the high-voltage battery isolated using the manufacturer’s safety procedure before handling its sense wiring.
- Test channel H wiring for a short to voltage, damaged insulation, or a poor connector using the wiring diagram and manufacturer’s specifications.
- If the harness tests correctly, check the battery voltage-sensing and control circuitry for a channel H input fault.
Common fixes
- Clean, reconnect, and secure a loose or corroded channel H connector.
- Repair wiring or insulation that is shorting channel H to voltage.
- Replace damaged channel H terminals or harness sections.
- Repair or replace the faulty sensing or control circuitry if the wiring is sound.
Can I keep driving?
Limit driving because the vehicle may reduce power or restrict charging when it cannot trust the channel H reading. If the vehicle enters limp mode or its power changes unexpectedly, pull over safely 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.