Nissan — P155b-00 Repack

The ECM controls the heater via a duty cycle (pulse-width modulation). When the ECM detects that the heater’s current draw or resistance is out of range—or when the sensor fails to reach operating temperature in the expected time—it sets P155B-00.

Use a scanner to check for , a technical service bulletin (TSB) covering this issue in many Nissan models. Perform a radar alignment check. Inspect the CAN bus wiring for faults. nissan p155b-00

With the sensor removed or disconnected: The ECM controls the heater via a duty

In plain English: The engine control module (ECM) has detected an irrational or unexpected electrical behavior in the heater circuit of the (often called a "wideband O2 sensor") located on Bank 1. This is not simply a “dead” sensor—it’s a rationality check failure. The ECM sees voltage, current, or resistance values that don’t make sense based on engine operating conditions. Perform a radar alignment check

Nissan often uses a dedicated 15A or 20A fuse for the A/F sensor heater circuit (sometimes labeled “A/F HTR” or “ENGINE SENSOR”). If the sensor shorts internally, it can blow this fuse. Always check fuses first.

In this article, we will break down what the P155B-00 code means, why it happens, common symptoms, and how to fix it. What is the P155B-00 Code?