jl-c

Try checking resistance from battery connectors to under bonnet. Only needs a few Ohms to cause a voltage drop, which will in turn behave like a battery fault.

sounds to me like a slipping auxiliary belt.

your missing the ashtray, can't help with the part number, sorry.

I know Audi say "sealed for life" but I don't trust this statement and suspect it is only a marketing ploy. What is the considered wisdom on this? Has anyone replaced the charger oil?

S4 75,000m at present.  

I had our VW Passat 2.0 Tdi Bluemotion mapped. They reversed the VAG emmissions patch and did a stage 1 remap. Everything better, more acceleration, more torque , more mpg ( about 10% ) and a much more drivable car. I used MPG tuning in Cannock Staffs. Best £300.00 I've spent!