What it means
The BMS detects a circuit range/performance 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 measures a cell group's voltage through sense channel Q and checks that it tracks within an expected range. This code sets when the Q reading is outside the acceptable range or does not perform as expected, even if the circuit is not simply open or shorted.
Common causes
Most likely first.
- Sense voltage drifted
- High-resistance contact
- Sensor element aged beyond calibration window
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 channel Q live voltage with nearby cell-group readings across the recorded operating conditions for a persistent mismatch.
- With the vehicle powered down as specified by the manufacturer, inspect channel Q wiring and connectors for corrosion, looseness, or damage that could add resistance.
- Have a qualified hybrid technician measure channel Q contact resistance and wiring continuity against the manufacturer's specification.
- Check whether the channel Q signal drifts relative to neighboring cell-group readings using the manufacturer's scan-tool procedure.
- If wiring and connections are sound, test the channel Q sensing element and battery monitoring module input for calibration drift using the manufacturer's procedure.
Common fixes
- Clean or repair a high-resistance channel Q connector or terminal.
- Repair channel Q wiring with excessive resistance or damage.
- Replace the channel Q sensing element if testing confirms it has drifted outside its calibration range.
- Repair or replace the battery monitoring module if its channel Q input fails testing.
Can I keep driving?
Avoid long trips and heavy loads because the vehicle may limit power or enter limp mode, and charging may be slowed or refused. A persistent channel Q measurement error can reduce usable electric range, 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.