What it means
The BMS detects a circuit fault on voltage sense channel L 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 measures a battery cell group through voltage sense channel L. This circuit code means the BMS has detected a fault in the channel L measurement circuit, so it cannot rely on that cell-group reading; the code alone does not specify the fault type.
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
- Record freeze-frame data and compare live channel L voltage with neighbouring channels to see whether the issue is isolated to L.
- With the vehicle powered down using the manufacturer's high-voltage safety procedure, inspect channel L wiring and connectors for looseness, corrosion, or physical damage.
- Check that channel L connector pins are seated and clean, and inspect the harness for chafing that could create an open or short.
- Have a qualified hybrid/EV technician test channel L wiring continuity and isolation using the manufacturer's procedure.
- If the wiring and connections pass, have the battery monitoring module's channel L input checked against manufacturer specifications.
Common fixes
- Secure a loose channel L connector and clean corroded terminals.
- Repair an open, shorted, or damaged section of channel L sense wiring.
- Replace damaged channel L connector terminals or connector housing.
- Replace a faulty battery monitoring module only after channel L wiring tests pass.
Can I keep driving?
The BMS may limit power or charging because it cannot rely on channel L's cell-group reading. Avoid demanding driving and arrange diagnosis promptly; stop safely if a stop warning appears or the vehicle loses power unexpectedly.
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.