What it means
The BMS detects a circuit intermittent/erratic fault on voltage sense channel Q 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 monitors cell-group voltage through sense channel Q and checks for a stable signal. This code sets when the channel Q reading becomes intermittent or erratic, preventing reliable tracking of that battery group.
Common causes
Most likely first.
- Sense connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
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 data and review channel Q live voltage alongside nearby cell-group readings for sudden jumps or dropouts.
- With the vehicle powered down as specified by the manufacturer, check that the channel Q connector is seated and its pins are clean, secure, and undamaged.
- Inspect channel Q wiring and its ground reference for looseness, damage, or routing that could allow vibration-related contact loss.
- Have a qualified hybrid technician check channel Q continuity and ground stability against the manufacturer's specification, including under approved movement or vibration tests.
- If wiring and connector checks pass, test the battery monitoring module's channel Q input using the manufacturer's diagnostic procedure.
Common fixes
- Reseat and secure the channel Q sense connector.
- Clean or repair loose, corroded, or damaged channel Q connector terminals.
- Repair channel Q wiring or ground connections that make the signal unstable.
- Repair or replace the battery monitoring module if its channel Q input is intermittent.
Can I keep driving?
Avoid long trips and heavy acceleration because the vehicle may suddenly limit power or enter limp mode if the channel Q signal drops out. Charging may be interrupted, so arrange prompt diagnosis by a qualified hybrid technician.
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.