What it means
The BMS detects a circuit 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 uses sense channel Q to measure a cell group's voltage and monitor the high-voltage battery. This code sets when the channel Q circuit has a fault that prevents the module from trusting that measurement; it does not specify whether the signal is low, high, or intermittent.
Common causes
Most likely first.
- Open or short in the voltage-sense wiring
- Loose, corroded, or damaged connection
- Battery monitoring module fault
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 neighboring cell-group readings to look for a missing or implausible value.
- With the vehicle powered down as specified by the manufacturer, inspect channel Q wiring and connectors for opens, shorts, corrosion, looseness, or physical damage.
- Have a qualified hybrid technician test channel Q wiring for continuity and shorts using the manufacturer's isolation procedure.
- Check channel Q connector contact quality and resistance against the manufacturer's specification.
- If the wiring and connections pass, test the battery monitoring module's channel Q input according to the manufacturer's diagnostic procedure.
Common fixes
- Repair an open or short in channel Q voltage-sense wiring.
- Clean, secure, or repair damaged or corroded channel Q connector terminals.
- Repair or replace the battery monitoring module if its channel Q input is faulty.
Can I keep driving?
Limit driving because reduced power or limp mode may occur, and charging may fail or be restricted. The module cannot rely on the channel Q cell-group measurement, 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.