Replace oxygen sensor code: P0135 HO2S-11 what does that entail?

What is your question?

Check engine light has been on and won't go away. Lots of repairs already done. Yet light still on. Tried putting distilled water in cooling system. Don't know what to do, or who to see.

What makes this problem better or worse?

Nothing, the check engine light stays on till I shut the car off, and goes back on when I use the car again, whether it's a few minutes, a few hours, or several days.

How long has your 2004 Chevrolet Impala had this problem?

Several weeks