O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)

What does this mean?

Code P0138 indicates the downstream O2 sensor on Bank 1 is reading persistently high voltage.

Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Nissan Titan models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.