What it means
The BMS detects a circuit intermittent/erratic fault on voltage sense channel U 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 BMS uses channel U to measure the voltage of a cell group in the high-voltage battery. This code sets when the channel U reading is intermittent or erratic, often because its connection or ground reference is unstable, and the BMS may respond by limiting battery operation.
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 watch channel U's live voltage beside adjacent cell-group readings for sudden jumps or dropouts.
- With the vehicle safely powered down under the manufacturer's high-voltage procedure, check that the channel U connector is fully seated and its pins are clean and undamaged.
- Inspect channel U's harness and ground-reference connections for looseness, strain, or chafing that could change with vibration.
- Have a qualified hybrid technician check channel U continuity and connector stability using the manufacturer's approved procedure.
- If the connection and wiring are stable, test the channel U ground reference and monitoring-module input against the manufacturer's specification.
Common fixes
- Reseat and secure the channel U connector.
- Clean or repair channel U pins with intermittent contact or corrosion.
- Repair loose or damaged channel U wiring and ground-reference connections.
- Replace the battery monitoring module only if its channel U input is confirmed unstable.
Can I keep driving?
Avoid hard acceleration and long journeys if power is reduced, because the BMS may limit output and interrupt charging. Arrange prompt diagnosis and stop if a battery safety warning appears.
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.