What it means
The monitored voltage for hybrid/EV battery C is higher than the control module’s expected range.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The battery control system monitors the voltage of hybrid/EV battery C, one monitored section of the high-voltage pack. This code sets when battery C's reported voltage is above the range the module expects, which can reflect overcharging, a high-biased sense reading, or an imbalanced cell group.
Common causes
Most likely first.
- Charging system overvoltage
- Sense circuit drifted high
- Pack cell imbalance approaching service threshold
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 battery C's reported voltage with other monitored battery sections and charging conditions to see when the high reading occurs.
- With the vehicle powered down, visually check accessible low-voltage sense wiring and connectors for damage, looseness, moisture, or corrosion; do not open the high-voltage pack.
- Use a scan tool to watch battery C voltage during the operating conditions in the freeze frame and check whether the reading stays consistently high or changes with vibration or charging.
- Have the battery voltage-sense circuit for section C checked for drift, poor connections, and continuity using the manufacturer's procedure.
- If the sense circuit checks out, have the high-voltage pack evaluated for imbalance and the charging system checked for overvoltage by a qualified hybrid technician.
Common fixes
- Repair a loose, damaged, or corroded battery C sense-circuit connector or low-voltage harness.
- Repair a drifting battery C voltage-sense circuit or its connection as specified by the manufacturer.
- Correct a charging-system overvoltage condition.
- Service or replace the affected battery modules if testing confirms an imbalance.
Can I keep driving?
Avoid hard acceleration and long trips if power is reduced, charging is restricted, or the vehicle enters limp mode; the system may limit or disable hybrid operation. Arrange prompt diagnosis, and do not touch high-voltage components.
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.