someone please explain why i might need to adjust "exhaust gas sensor sensitivity".

 

I believe it senses exhaust pollutants, IE smog, and changes the HVAC to recirculate mode. So, the more sensitive it is set, the sooner and more often, it will make the change from fresh to recirculate.

 

Does anyone know where this sensor is, mine does not seem to be working. I have tired both the highest and lowest sensitivity settings, however neither results in the air EVER being changed away from recirculation while set to "auto".

 

The reason why it is staying in recirculate mode likely has nothing to do with smog sensor sensitivity.

Instead, it is because the climate control system on the ES is set up to default to and stay in recirculate mode whenever the outside temperature is above about 75 degrees. (See page 356 of the 2013 ES manual, page 374 or the 2017 ES manual, or other similar page for other model years). To me, the wisdom of Lexus setting the system up that way was misguided because I find that, when the climate control system operates in the recirculate mode continuously, the air quality becomes somewhat stale.

 

Ah, I see, thank you for the info. I guess this means that it is near useless in Texas.