ok so ive been having this problem you can look at it in the s car model line cause i dont want to put it back up here but i vag'ed it and this is what it said so please help with what you think
7 Faults Found:

18010 - Power Supply Terminal 30: Voltage too Low

P1602 - 35-10 - - - Intermittent

18058 - Shareware Version. To Decode all DTCs

P1650 - 35-00 - Please Register/Activate

17964 - Shareware Version. To Decode all DTCs

P1556 - 35-10 - Please Register/Activate - Intermittent

17521 - Oxygen (Lambda) Sensor: B1 S1: Internal Resistance too High

P1113 - 35-10 - - - Intermittent

17539 - Shareware Version. To Decode all DTCs

P1131 - 35-10 - Please Register/Activate - Intermittent

16815 - Shareware Version. To Decode all DTCs

P0431 - 35-00 - Please Register/Activate

16805 - Warm Up Catalyst: Bank 1: Efficiency Below Threshold

P0421 - 35-00 - -

 

Hello,
This is what the Bentley Trouble Codes read and I am not sure if this helps at all.

Vag Code SAE P-code Description
18010 P1602 - as you have written only addition is (B+)
18058 P1650 - Data Bus Powertrain missing message fr.instrument panel ECU
17964 P1556 - Charge Press Contr.Negative Deviation
17521 P1113 - Bank 1- Sensor 1 Internal Resistance too high
17539 P1131 - Bank 2-Sensor 1 Internal Resistance too high
16815- The Bentley has nothing on this code and it is not written
16805- The Bentley has nothing on this code and it is not written
Please note;The Bentley Manual I am using is for the A6/S6,allroad and RS6 '98-2004.
Hope this is of some help.

 

These codes 17521 & 17539 have to do with the O2 sensors.
16815 & 16805 have to do with catalysts.