So basically, I took my car to advance auto parts because my engine light came on. So they told me that the code was P0420, and it was bank 1. I need to pass emissions on the 22nd and i got an estimate to change the catalyc converter but the only problem is that it will cost me around 600 to 700 dollars. Don't have the money right now. So I talked to a friend and told me changing the O2 sensors might fix the problem. Any suggestions? The engine light goes off times, yesterday it turned off and as I was drivin it to emissions today to take advantage of that, it came back ok

Any suggestions would be helpful. Thank you.