O2 Sensor 1 no voltage

Hey all,

I just bought my 2005 Tacoma Trd sport last week and I recently bought a obdII wifi scanner. Plugged it in today and drove about 7 miles on the street and realized that my o2 sensor 1 had 0 volts the whole time. Didnt say which bank or sensor because I had no diagnostic trouble and the check engine light didnt come on, but im pretty sure its upstream. I dont know if this is a problem, or if its just normal. I was averaging 15.6 mpg on the street.

Im new to Tacomas and I absolutely love mine but im not familiar at all with the 4 liter. any response will be appreciated. thanks!

Also, I got a smog check and passed about a week ago, which also confused me.

 

O2 sensors take time to warm up.

Try driving for 20 mins and then check it.