Oxygen sensors
 

As my car has a lot of miles, with everything I´m replacing, I will replace the PRE-CAT Oxygen sensors as well.
Which ones to buy? Bosch?
Do I have to make some adaptations after the replacement? I´ve read about some "readiness codes"...

I think the Bosch ones are OE but i'm not 100% sure on that. However they are a good quality replacement so you should be fine.

Probe Lambda Sensor BOSCH 0258007351 is the one you want.

I think fitment is quite involved so do report back on how much it costs to install them - it will help others.

I don't think Bosch make the plug and play ones anymore - or at least I couldn't find them.
The suggested replacement has a different plug with an adapter to modify the factory plug from what I recall.

NTK (NGK's brand in the case of O2 sensors) make a direct plug and play version that I have used without any problems on my S8 for around 5 years now.

https://www.autodoc.co.uk/spares-sea...ord=0258007351
The Hella one looks good value.

The inlet manifold has to come out http://www.corradov8.com/pics/banghead.gif

Sorry - I was thinking D2 O2 sensors.
Just realised this is posted in the D3 engine section...

Is BFM 4.2 an inlet manifold out job for the O2 sensors?
A bit silly, they're pretty much a service item!

One of them is. I seem to remember the engine has to come out for the other side. Two of the many reasons I don't work on D3s :tuttut:

Inlet manifold out for the N/S pre cat sensor (in a RH Drive car)
and the LH (Drivers) Side one isnt accessible and requires engine out :-(

Which Engineer got a promotion for that idiocy?

...If I ever buy a D3, it will have 2 more cylinders (And probably 2 x the problems!)

I should imagine once the German engineer realised his error he offered himself for sacrifice! :(

I bought the two precat sensors now. Why would it be necessary to remove the intake manifold?? It makes no sense as the manifold is the last thing that is on the way! Anyone?

Because Audi decided to make the only tool access to one of the sensors (can't remember which) directly through the space occupied by the inlet manifold. There really is no other way to get to it with the engine in the car. It is very silly indeed.