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.

A: If the code returns, re-check your work for any missed wiring issues. If the wiring is perfect, the next step is to have a dealer-level diagnostic scan performed to test the ECM or IPDM E/R for internal failure, though this is significantly rarer than a sensor or wiring issue.

If the code returns after cleaning, use a multimeter to check the sensor plug. Disconnect the sensor harness connector. nissan p155b-00

: The vehicle’s fuel-saving automatic engine shutoff feature (Idle Stop/Start) stops working because the ECM cannot verify battery health.

The charging voltage may stubbornly lock at a flat 13.8V or drop dangerously low to 12.2V because the ECM can no longer adjust alternator output dynamically. The '-00' suffix typically indicates that there is

What is mal function error after scanning?

: Open or shorted circuits in the wiring harness connecting the Engine Control Module (ECM) to the battery heater relay. Blown Fuse If the code returns after cleaning, use a

If the wiring and connectors test good, but the sensor still fails to provide a correct signal, the sensor itself is likely defective.