Hello everybody and thanks in advance for reading this,

I have a couple of questions relative to oxygen sensors which I couldn't find through the search

1) I got the error code for O2 sensor 16518, Bank 1 Sensor 1. Is this the pre-cat sensor on the passenger side?

2) Never replaced O2 sensors before. Is the DIY a big deal? If not, do you happen to know where I can find a tutorial? Can't seem to find any on the web.

3) I also got the code 16805 for Catalyst converter in bank 1 - efficiency below threshold. Does this mean the catalyst converter is shot or it just connected with the bad O2 sensor (which would make sense if it's the pre-cat one)

I vaged and erased all the codes 2 weeks ago and they pop up again so I'm assuming they are for real.

Thanks in advance for any help!!
j_ripper19