O2 sensor not ready for inspection

Hello,
I am new here so I want to say hi.
And also I'm not much of a mechanic.

My inspection is out and I am still trying to get it passed.

It keeps saying the O2 sensor is : not ready " (upstream)
The heated sensor is okay
Keep in mind through all this, the check engine light has never come on.

Initially earlier this year I left my hazard blinkers on all night and my battery died.
It was light out when I hit button and for some reason I didn't notice.
I replaced the battery and tried to get it inspected 3 weeks later and it wouldn't pass. O2 sensor not ready.
Have driven it about 2,000 miles. Same result.
Don't know if this has any thing to do with the O2 sensoe situation, but want to give all information that I can.

Replaced the sensor and have driven another 180 miles, but with the same result.
O2 sensor not ready. And still the check engine has never come on.
Also says: catalyst not ready.

Any help or ideas.
I lack knowledge and am trying to avoid spending a lot of unnecessary money.

The truck runs great, best vehicle I have ever owned.
And has always passed inspections.
I bought it used in 2009

2007
4 cyl
automatic
2 wheel drive

Thank you,
sandfisher