W211 E320 CDI 2008 - Oxygen Sensor problem ?

[carrotbay]

Hi

I have a 2008 W211 E320 CDI (V6) with 50k miles. I have noticed some performance issues recently with a loss of power and quite a bit of soot from the exhaust. I connected a OBDII tool and pulled the following errors:

P0130
P0135
P0030
P2A00

I think that these all seem to point towards a faulty oxygen sensor. Is this right?

Where is the sensor located on the engine or is it down the exhaust somewhere? (I want to change myself)

Thanks