: The alternator engages at maximum capacity when you lift your foot off the accelerator or hit the brakes, converting kinetic energy into electrical energy.
Potential issues with the Auto Start/Stop system (if equipped). Unusual battery charging behavior (fluctuating voltage). 2. Potential Causes
Over time, the battery may suffer from chronic undercharging, leading to sluggish startups on cold mornings. Step-by-Step Diagnostic and Repair Protocol
If you're experiencing issues with your Nissan vehicle and have seen this code, it's best to address it promptly to ensure your vehicle runs safely and efficiently.
: Modern Nissans feature an "intelligent" battery sensor mounted directly on the negative battery terminal. If this sensor suffers internal failures, the ECM cannot get reliable data.
Unplug the small electrical harness feeding into the current sensor. Inspect the internal pins for bend deformities or moisture. Use a dedicated electrical contact cleaner spray if any dirt is present. Trace the harness back a few inches into the main loom to verify that no wires have melted against hot engine components. Step 4: Voltage and Resistance Validation
Dry thoroughly and reconnect the clamps tightly. Loose connections frequently generate false current data. Step 3: Check the Wiring Connector
The P155B-00 code can be caused by several factors, including:
The Nissan P155B-00 code, while specific, is a very manageable diagnostic challenge. It is your car's way of telling you there is a fault in the electrical energy management system, most commonly due to the battery current sensor or its wiring. By following a logical diagnostic path—starting with the battery and alternator, then checking grounds and signal circuits—the majority of owners can identify the culprit component. While an OEM replacement cable may be a bit more expensive than a generic part, it is a direct-fit, reliable solution that restores your Nissan's charging system to full operational efficiency, saving you from future battery issues and preserving your vehicle's fuel economy.
If your vehicle is throwing this code, let me know the of your Nissan (e.g., Dayz, Roox, Note), and whether you have recently replaced or jumped the battery . I can guide you on the specific reset procedure or battery specifications required for your model. Share public link
Disconnecting the sensor deliberately to force the alternator into a continuous 14V charging state will lock this code permanently in the ECM. Common Symptoms to Watch For
Potential slight fluctuations in engine RPM if the alternator load switches erratically. JustAnswer Common Causes Defective Sensor
Source. All rights reserved. © 2026
