What it means
The BMS detects a circuit low 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 reads cell-group voltage through sense channel Q to monitor the high-voltage battery. This code sets when the Q signal falls below its expected range, leaving that cell-group measurement unreliable.
Common causes
Most likely first.
- Sense wire shorted to ground
- Open in sense wire
- Connector pins corroded - high contact resistance
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 compare live channel Q voltage with adjacent cell-group readings to confirm whether the signal is abnormally low.
- With the vehicle powered down as specified by the manufacturer, inspect channel Q wiring for a short to ground, an open, damaged insulation, or a loose connector.
- Have a qualified hybrid technician test channel Q for a short to ground or an open using the manufacturer's isolation procedure.
- Inspect channel Q terminals for corrosion and check contact resistance and continuity against the manufacturer's specification.
- If the wiring and connector pass, test the battery monitoring module's channel Q input according to the manufacturer's diagnostic procedure.
Common fixes
- Repair channel Q wiring that is shorted to ground.
- Restore an open in the channel Q sense wire.
- Clean or repair corroded channel Q connector terminals and ensure a secure connection.
- Repair or replace the battery monitoring module if its channel Q input is faulty.
Can I keep driving?
Avoid long trips and demanding acceleration because reduced power or limp mode may follow from the unreliable channel Q reading. Charging may be limited or fail, 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.