Lazy 02 sensor code

[jdan]

Forgot what number the code was but it pointed me to the sensor on the passenger side at the manifold.
I was gonna just replace it but on closer inspection I saw black soot around the last cylinder of the manifold and the studs to head are gone.
There is no noise coming from it and I've replaced these studs and manifolds on 5.4L's in the past so I can say its not a fun job.
So to the point could this leak be causing the cel? Or should I just toss a sensor on and see what happens..
It's most likely original on 183k.
Thanks in advance.

 

[Canadian Expy]

I'd fix the leak first, then see if it still throws the code.
Mines throwing code right now, because of a leak ...

 

[BakerEdition]

I disagree...I have two broken heads on mine and no codes or CEL....I would replace both upstream O2's it will only improve drive ability and MPGs.

 

[jdan]

Yea these are the codes. The pathfinder is pretty much saying common fix is RR the O2 sensor.
So I'm just gonna replace them all since I doubt they have ever been replaced.