Nissan P155b-00 Info

Using a multimeter:

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

While this code is often due to a part defect or normal wear, you can reduce the risk:

The P155B-00 code is a manufacturer-specific diagnostic trouble code (DTC) for Nissan vehicles. In plain English, this code translates to:

"Engine Coolant Bypass Valve 'A' Control Stuck Closed." nissan p155b-00

The '-00' suffix typically indicates that there is no additional sub-code or specific circuit fault—it is a general logic failure, meaning the engine control module (ECM) has detected that the bypass valve is not operating as commanded.

Assuming you mean a feature description/spec sheet for the Nissan P155B-00 (engine control module / part), here’s a concise feature spec. I’ll assume OEM replacement module functionality for a modern Nissan vehicle — tell me if you want it targeted to a specific model/year.

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. Using a multimeter: If you are a DIY

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.

Q: Will P155B-00 clear itself? A: Unlikely. Even if the valve temporarily frees itself, the code will remain in the ECM until cleared with a scan tool. The condition usually recurs quickly.

Q: Can a bad thermostat cause P155B-00? A: No. The code specifically targets the bypass valve, not the main thermostat. However, replacing both components together is often good preventative maintenance.

Q: Does P155B-00 affect emissions testing? A: Yes. In most states, a check engine light with an active DTC is an automatic fail on the OBD-II emissions test. Assuming you mean a feature description/spec sheet for

Q: My Nissan has P155B-00 but runs fine. Do I still need to fix it? A: Yes. The valve can fail fully closed at any moment, leading to sudden overheating. It is not a benign code.

Nissan has acknowledged cooling system valve issues on several models. For example, NTB12-055 and NTB16-085 cover certain Rogue, Altima, and Sentra models with P155B-00-related symptoms. These TSBs often prescribe a software update and/or valve replacement.

Check with a Nissan dealer using your VIN to see if your vehicle qualifies for a warranty extension or free repair—especially if you are under 80,000 miles.