engine management light on - A3 2009 TDI 170HP

[pform]

Guys,
Just this morning the engine management light came up, in amber colour. Car has 17.5K miles. First thing I've done was to call a friend who run an independent audi garage. I was at his place after 30 mins, car was plugged and a printout produced ... The diagnostic read 2 "events"
1 "Exhaust gas pressure sensor 1 implausible signal"
2 "Particulate filter differential pressure sender implausible signal"
Anyway, friend said it not so critical and probably some sensors need to be replaced. Dealer will do it under warranty However something more alarming came up... the diagnostic read that total milage of my car was 28475!! This was something even new to this experienced technician who said that probably the dash computer was sending some sort of wrong data to the diagnostic...?? I mean, my car was bought brand new with just 2 miles on the ODO! Can anyone tell me more about this??
Thanks

[daycartes]

Hi as far as the mileage goes, 17500 roughly equates to 28500 km so perhaps this would explain the difference.
Hope this helps,

daycartes

[a8 tech]

pressure difference sensor defective
exhaust temp sensor blocked due to pressure difference sensor reading 0
mileage is stored in km in all control units