12v oxygen sensor replacement

[Peter Guthrie]

Lately as the cold weather has started I've noticed a slight
hesitation during accelaration when the engine is cold. It
clears up after a few miles though.

Doing some searching of the archives it looks like the oxygen
sensor could well do with replacement as the car is approaching
80,000 miles on the original. I also plan to change the spark
plugs too.

It's a 2.6 12 valve (engine code ABC),very similar to the 2.8 12 valve...

How many sensors are there?

Where are they?

Does anyone have a procedure for removing them? any special
tools required?

Is there anyway I can diagnose the sensors with VAG1551 clone
software on a laptop?

If replacing, is there any point in using the geninue VAG Audi
part or will a generic O2 sensor be just as good (I understand
the wires may need splicing into the original loom).

I'm really looking for some BTDT experience.

TIA

Peter