Why can I not get my check engine light to turn off?

What is your question?

The check engine light on our 2004 Honda Civic LX came it was throwing the code for the downstream O2 sensor. We replaced it and the light went off. A week later the check engine light came back on throwing the code for the upstream O2 sensor. We replaced it the light went off but the next day came back on. It was still throwing the code for the upstream O2 sensor. Thought the sensor was bad replaced it with another new one same type. Did a hard reset check engine light came back on. Was told to drive it 350 miles did that. Got the gas mileage of a pick up truck. Thought that it might be the brand went and got the expensive one. Still the check engine light is on. what do we need to do? Thanks

What makes this problem better or worse?

We thought changing the sensor would fix it

How long has your 2004 Honda Civic had this problem?

Four Weeks