I recently purchased a 2006 Audi A4 Quattro 2.0T FSI - my very first Audi - details below, which generally I am very happy with, except for some issues I've been having with numerous CEL's coming on every couple of weeks or so, and an oil leak.

Year of car: 2006
Model of car : A4 S-line
What engine & TIP or 6sp : 2.0T FSI / 6sp manual
Miles : 110,000
FWD or Quattro : Quattro
6. Any CELs or stored codes : P2261 and P0507

So the first time the CEL came on I took it to my local Audi garage and they diagnosed the fault as a faulty crankcase breather, which was replaced. A few weeks later, the CEL came on again, and this time I also noticed that the engine idle speed was fluctuating between 800 and 1400 rpm, which would seem to go away if I turn on the air con. So I got a friend to diagnose the codes, and the codes that came back were P0507 - Idle Control System, and P2261 - Boost Pressure Control.

Took it back to the Audi garage, explained the symptoms, told them the codes, and again they diagnosed it as the crankcase breather, and replaced it (under parts warranty, so at least that didn't cost me anything). They also adapted the throttle body. Yet the idling problem still persists. I'm not really mechanically minded, but from the research I've been doing, these symptoms seem to be consistent with a failed PCV - so sorry if this is a silly question but is PCV just another term for the crankcase breather, or are they two separate components? Or is there another common fault that could be causing this? Is there anything that doesn't involve dismantling the car that I can check? I have checked the oil cap, there is no oil around it, it comes off easily when the engine is running and there is no suction (which I'm assuming is good?)

I also had the diverter valve replaced, and boy did that make a difference to the performance! So I'm hoping that's taken care of the P2261 code at least - time will tell.

With regards to the oil leak, this was eventually traced to the vacuum pump, and oil was running down the wiring loom on to the gear box and out through the under-tray on to my driveway. I had this fixed by another (non-Audi) garage, or so I thought, as it's still leaking - I've posted a picture of where the oil is coming from, which looks to me like it's been bodged with sealant rather than replacing the seal - is this a big deal to replace? I've read that this is not an easy job with up to 5 hours labour...

Any advice would be most appreciated, as I'm really starting to develop a love-hate relationship with this car! As the saying goes... "when she was good, she was very, very good, and when she was bad she was horrid!"