Ensure the alternator is providing 14.8V14.8 cap V while the engine is running.

Clear any corrosion from battery terminals and connectors in the CAN network.

The battery may die quickly if the current sensor is not informing the alternator to charge properly. Diagnosis and Troubleshooting

If the alternator is not charging properly, the system can enter a protective state, triggering this code. Symptoms of a P155B00 Code

Poor wiring connections, specifically in the CAN bus network or around the battery, can cause data corruption that triggers this code.

Ensure the battery is in good health and has at least 12.6V12.6 cap V when the car is off.

If the wiring and sensors are functional, the ECM may require a firmware update or, in rare cases, a complete replacement.