O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 1)

What does this mean?

Code P0154 indicates a problem with the upstream oxygen sensor on Bank 2. This sensor monitors the air-fuel ratio before the catalytic converter on the opposite bank.

Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Mazda Cx-9 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.