Nissan P155b-00

Code Meaning: P155B-00

  • Description: This code is associated with issues related to the Electric Throttle Control (ETC) system, particularly problems with the throttle valve's opening angle, or there might be a fault in the way the throttle valve operates.

Diagnostic & Repair Steps

1. Inspect the Battery Terminal and Sensor

  • Open the hood and locate the negative battery terminal.
  • Look for the black plastic sensor module clamped around the negative cable.
  • Check for damage: Is the sensor cracked? Was it forced back onto the terminal?
  • Check for aftermarket parts: If a generic battery terminal clamp has been installed (instead of the OEM clamp with the sensor), the sensor must be replaced or re-installed correctly.

2. Check Battery Health

  • Use a battery tester to ensure the battery is healthy. If the battery is failing, replace it first. Clear the code and see if it returns.

3. Inspect Wiring

  • Follow the small wiring harness coming off the sensor. Check for any signs of corrosion (green/white residue) on the connector pins or cuts in the wire insulation.

4. Sensor Replacement

  • If physical inspection checks out and the battery is good, the Battery Current Sensor is the most likely culprit.
  • Part Cost: usually between $50 – $150 USD depending on the model.
  • Installation: It typically unbolts/unclamps from the negative cable. Ensure you disconnect the battery before replacing it to avoid shorting the sensor.

5. Calibration / Relearn

  • On most modern Nissans, after replacing the sensor or battery, you must perform an "Idle Air Volume Relearn" or generic OBDII code clearing. Some vehicles require the steering angle sensor reset or an ECM relearn using a professional scanner (like Nissan Consult III), though simple sensor replacement often just requires clearing the code with a standard OBD2 scanner.

What Causes the P155B-00 Code?

Several underlying issues can trigger this DTC. In our experience repairing Nissans, here are the most common culprits: nissan p155b-00

| Cause | Likelihood | Description | |-------|------------|-------------| | Faulty Coolant Bypass Valve | High | The internal mechanism seizes, or the electric motor fails. This is the #1 cause. | | Wiring or Connector Issues | Medium | Corroded pins, broken wires, or loose connectors at the valve harness. | | Low Coolant Level | Medium | Air pockets in the system prevent proper valve actuation or confuse the temperature sensor. | | ECM Software Glitch | Low | On rare occasions, a software update from Nissan resolves false P155B-00 codes. | | Blown Fuse | Low | The bypass valve circuit may share a fuse with other components. |

What is Nissan P155B-00?

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." Code Meaning: 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.

7. Special Notes

  • Do not assume the actuator is bad without checking wiring and performing the active test.
  • Some Nissan models require the engine to be at operating temperature (ECT > 75°C) before the ECM tests the actuator.
  • After repair, clear DTC and perform a drive cycle: idle for 2 min, then light acceleration to 3000 RPM, decel, and repeat 3 times.

It looks like you're referencing a Nissan Diagnostic Trouble Code (DTC) — P155B-00.

Here is the breakdown of what this code typically means for Nissan vehicles: Description: This code is associated with issues related

Parts Needed

  • Genuine Nissan coolant bypass valve (Part numbers vary: 22380-6CA0A or 22380-6CA0B for many models)
  • Fresh Nissan coolant (1–2 gallons)
  • New O-rings or gasket (included with some valves)