Nissan P155b-00 May 2026

The Engine Control Module (ECM) monitors the current flowing through the battery via the Battery Current Sensor. This sensor is attached to the negative battery terminal clamp or the cable itself.

The ECM uses this data to regulate the charging voltage (variable voltage charging system) to improve fuel economy and extend battery life.

Code P155B-00 sets when the ECM detects that the signal from the Battery Current Sensor is out of the expected range, inconsistent, or does not correlate with other data (like battery temperature or voltage). Essentially, the computer cannot accurately read how much electricity the car is using or charging.

Check the reservoir and radiator (when cold). Top up with Nissan Genuine Blue coolant (or equivalent HOAT). Burp the system to remove air.

Using a multimeter:

| Service | Estimated Cost (USD) | |---------|----------------------| | Diagnostic fee | $100 – $150 | | Coolant bypass valve (OEM) | $120 – $250 | | Coolant & supplies | $30 – $60 | | Labor (1.5 – 2.5 hours) | $150 – $300 | | Total at dealership | $350 – $650 | | Total at independent shop | $250 – $450 | | DIY cost | $150 – $300 |

Note: Prices vary by region and model year. V6 engines often require more labor due to tighter access.

Use a bidirectional scan tool (not just a basic code reader). Clear the code and perform a road test to see if P155B-00 returns immediately.

If you have this code, check your negative battery terminal first. If a mechanic recently changed your battery and did not reinstall the factory sensor correctly (or damaged it), that is the cause. If the terminal looks stock and undamaged, replace the Battery Current Sensor.

The Nissan fault code specifically refers to a malfunction in the Battery Current Sensor

. This sensor monitors the amperage produced by the alternator to maintain the battery's charge and oversees the current flow for various vehicle components. JustAnswer Understanding P155B-00 Definition : Battery Current Sensor Circuit Malfunction. Primary Function nissan p155b-00

: The sensor tracks how much current is going into or out of the battery. The Engine Control Module (ECM) uses this data to manage the alternator's output and optimize fuel efficiency through the smart charging system. Illuminated Check Engine Light (MIL). Charging system warnings.

Potential slight fluctuations in engine RPM if the alternator load switches erratically. JustAnswer Common Causes Defective Sensor

: A failed battery current sensor unit located on the negative battery terminal. Wiring Issues

: Corroded, loose, or damaged wiring/connectors at the sensor. Battery Condition

: An aging battery that requires excessive amperage to charge may sometimes trigger sensor-related logic codes. JustAnswer Diagnostic Steps Visual Inspection

: Check the negative battery terminal for loose connections or corrosion on the sensor and its harness. Battery Test

: Ensure the battery itself is healthy and holding a charge (typically between 12.0 - 15.5 V Code Reset

: In some cases, resetting the code is recommended to see if it was a "soft" failure before replacing expensive parts. Sensor Replacement

: If the wiring and battery are confirmed good, the sensor assembly (often integrated into the battery cable) usually needs replacement. YarikSteel.RU or a specific part number for the sensor? NISSAN B13 and N14 Official Factory Workshop Manual Vol 1

Understanding the Nissan P155B-00 Error Code: A Deep Dive If you’ve recently scanned your Nissan and were greeted by the diagnostic trouble code (DTC) P155B-00, you might be feeling a bit stumped. Unlike common codes for spark plugs or gas caps, this one is specific and can affect how your car manages its electrical power. The Engine Control Module (ECM) monitors the current

In this post, we’ll break down what P155B-00 means, why it happens, and how to get your Nissan back to 100%. What is P155B-00?

The code P155B-00 typically points to an issue within the Energy Management Control system. In modern Nissan vehicles, the Energy Management system is responsible for monitoring how much electricity is being pulled from and sent to your battery to ensure peak efficiency.

While "P155B" is the main code, the "-00" suffix is a sub-type identifier indicating that no further specific subtype information is available—it's a general circuit or system fault. Common Symptoms When this code is triggered, you might notice: A Check Engine Light (MIL): The most obvious sign.

Charging Issues: The vehicle may not manage battery charging correctly.

Auto Start-Stop Failure: If your Nissan has the auto start-stop feature, it may be disabled because the system can't verify the battery's health.

Weak Starts: You might feel the engine struggling slightly more than usual during ignition. Potential Causes

Multiple components work together in the Energy Management system. P155B-00 is usually caused by:

Faulty Battery Current Sensor: This sensor sits on the negative battery terminal and measures the current flow. If it fails or sends a "low input" signal, the ECM loses its ability to manage energy.

Wiring or Connector Issues: Corroded or loose wires between the battery sensor and the Engine Control Module (ECM) or Intelligent Power Distribution Module (IPDM) can trigger this fault.

Weak or Dying Battery: Sometimes, a battery that can no longer hold a proper charge confuses the sensor, leading to a "ghost" code. Code P155B-00 sets when the ECM detects that

Alternator Problems: If the generator is under-performing, the energy management system may flag a circuit error. How to Fix It

Before you start replacing expensive parts, follow these diagnostic steps: 1. Check Battery Health

Ensure your battery is providing at least 11V at idle. Many electrical codes in Nissans are simply the result of a battery nearing the end of its life. 2. Inspect the Battery Current Sensor

Look at the sensor attached to your negative battery cable. Are the connectors tight? Is there any visible corrosion? Cleaning the terminals with electrical contact cleaner can sometimes resolve the issue. 3. Diagnostic Prioritization

If you also see codes P155E or P155F, Nissan service manuals recommend fixing those first, as they are often the "root" cause that triggers the P155B-00 secondary fault. 4. Clear the Code and Test

Use an OBD-II scanner to clear the code. Start the engine and let it idle for at least 20 seconds to see if the code returns immediately. If it does, the current sensor likely needs replacement. Summary Table What to Check Battery Voltage should be >11V at idle. Harness/Wiring Look for frayed wires near the battery terminals. Connectors Ensure the 2-pin or 3-pin sensor plug is seated fully. Alternator Check for steady output under load.

Do you have other error codes appearing alongside P155B-00, or did this code appear right after a battery replacement? What is mal function error after scanning?

For 90% of cases, the fix is replacing the coolant bypass valve assembly. Here’s how to do it:

If you are a DIY mechanic or a professional technician, follow this systematic approach: