Battery Module Fault
Your vehicle's hybrid or electric battery system is reporting an internal fault, similar to a phone battery that's no longer communicating properly with its charger. The battery module isn't functioning correctly and needs diagnosis or replacement.
The ECU monitors the battery module's internal voltage, cell balance, temperature, and communication signals. It detects faults when cell voltages drop below minimum thresholds, temperature sensors fail, or the module fails to respond on the CAN bus network.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cell Voltage | 3.0-4.2V per cell | Below 2.5V or above 4.3V per cell |
| Module CAN Communication | Responding within 100ms | No response or timeout error |
Code C1864 is classified as a serious fault. If your check engine light is flashing — not just steady — pull over safely and do not continue driving. A flashing CEL indicates an active misfire or critical failure that can cause catalytic converter damage within minutes or permanent engine harm within miles. Contact a certified mechanic immediately. Do not attempt roadside repairs on high-severity codes unless you are trained to do so.
Once the fault is repaired, C1864 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.