HI everyone im new here but this is my 3rd S4 i recently bought a 1 owner 2001 S4 with many upgrades but also a few issues im trying to get to the bottom of and here they are.
1 I get 2 fault codes on the Vag tool they are 16486 MAssair flow sensor signal too low
2 17539 Oxegen sensor B2S1 Internal Resistance to High Intermittent

I have checked the Mass air and it has been replaced so i went over all the connections and redid them still get the same code. I Know the o2 is a front sensor but im not sure witch one or how to test it.

The only other problem i have is interment abs signal on the brakes this i dont know were to start.

Here are the mods to this car that i know of
Porshe Black front rotors and calipers
Y pipe mod
Diverter valves
I belive its chipped as it has a M writin on the ECU and warranty seal but no idea by who
it has miltek exhaust and i belive downpipes

Any help on my three issues would be greatly appreciated.[/align]

 

can't help you on the vag-com and bentley stuff as for I have been slack'n in regards to getting them for myself... i will do so shortly.

in regards to your ABS light, check the brake fluid level and fill it up if it is low. I had a car that did the same thing, basically on radical turns, bumps in the road, or hard braking and the fluid was just a little low, filled it up and never saw it again..

Shawn