Engine issues 11 codes

[jamesb]

Long story cut short, the A8's Aux pulley failed.

The AA recovered the car back the last few miles to my place on battery power alone (over the tow limit for his van, and no trucks available).

Apparently, the car conked out again, he installed a new battery and continued the journey. It conked out again around 500 yards from my house.

I then had to recover the AA guy as he couldn't get the car started, and was parked on a blind bend.

He said the car just started to splutter and die, like it was suffering fuel starvation.

So I charged the battery up, and threw the code reader on it.

Codes

17521 Lambda B1S1 (knew this had failed and needed replacing)
16814 Catalyst System B2 Low Signal
16711 Knock sensor low signal
16946 System voltage low
17536 Fuel trim B1 lean
17538 Fuel trim B2 lean
16684 Cylinder misfire - unknown
16685 Cyl 1 misfire
16686 Cyl 2 misfire
18010 Power supply B+ terminal 30 voltage low

Now a few of those are due to low voltage (going to clear the codes and recrank and see if they come back with a fresh battery).

The aux belt tensioner still needs installation. However, I would have thought the car would run for a short while without the alt-charging.

It's the issue with the misfires that are bothering me. Something seems to have gone wrong on the recovery drive.

Is there any quirk with the A8 that may have contributed to these issues? maybe some insight that will help me focus on a particular area to get things running again.

Regards

James