Last month I bought an Audi A4 avant sline 
The engine light has now come on ! 
My mate has a reader and 2 codes have come up p0471 and p2196
I think one is a oxygen sensor and other an exhaust sensor? Is one connected to the other ? 
Should I change both or has something made them come on ? Thanks in advance

its far to complicated for me ! 

Not sure what "still a VAG" means for you on a Skoda forum.

There are VAG forums. There are AUDI forums. Heck, there are even AUDI A4 forums too.

Your A4 might as well be a Ford Mondeo if that's the only info your giving us

11 hours ago, Vfr400boy said:

I think one is a oxygen sensor and other an exhaust sensor?

On what you've told us so far, they could be synonyms, or even the same part.

Sorry I thort it was the same as an Octavia, 

think I will take it to a main dealer and get them to tell me what’s what etc 

1 hour ago, Vfr400boy said:

Sorry I thort it was the same as an Octavia,

And? I make that 4 different capacities and 6 different states of tune for petrol engines, and 4 states of tune for diesels.

Arrr sorry it’s a 2.0L tdi B8 , 58 plate , 120k on clock 

16 minutes ago, Vfr400boy said:

Arrr sorry it’s a 2.0L tdi B8 , 58 plate , 120k on clock 

Someone in the vcds sub forum would be able to guide further re fault codes - could be a sensor pre or post dpf - you could try a dpf regeneration, or if worse try a dpf clean additive or terraclean.

34 minutes ago, Vfr400boy said:

Arrr sorry it’s a 2.0L tdi B8 , 58 plate , 120k on clock 

In which case I was wrong; there are more potential capacities and states of tune than I already counted!

 

Anyway, you could put a multimeter across the electrical terminals on the oxygen sensors on the exhaust, looking for a value of about 0.7v I think.