Here's the result of the scan, clean modules removed:

VCDS-Lite Version: Release 1.2 Wednesday, 07 June 2017, 11:10:02:65169

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Address 01: Engine Labels: 4D0-907-560-AVP.LBL
Controller: 4D0 907 559 AA
Component: 4.2L V8/5V G 0002
Coding: 10753
Shop #: WSC 02629
VCID: 6DADB4263489
WAUZZZ4D63N001043 AUZ7Z0A2019960
7 Faults Found:
17831 - Secondary Air Injection System; Bank 1: Insufficient Flow
P1423 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16688 - Cylinder 4: Misfire Detected
P0304 - 35-00 - -
16686 - Cylinder 2: Misfire Detected
P0302 - 35-00 - -
16685 - Cylinder 1: Misfire Detected
P0301 - 35-00 - -
16687 - Cylinder 3: Misfire Detected
P0303 - 35-00 - -
16690 - Cylinder 6: Misfire Detected
P0306 - 35-00 - -
Readiness: 0000 0000

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Address 03: ABS Brakes Labels: 8D0-907-389.LBL
Controller: 4D0 907 389 E
Component: ABS/ESP allrad D57
Coding: 08397
Shop #: WSC 02313
VCID: 31156856E831
1 Fault Found:
01119 - Gear Recognition Signal
35-10 - - - Intermittent

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Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8L0 862 257 P
Component: CV-Pump, Alarm, RC D17
Coding: 16235
Shop #: WSC 02314
VCID: 42F7379A5D97
5 Faults Found:
01367 - Central Locking Pump Run Time Exceeded (Likely Leak)
35-00 - -
01371 - Alarm triggered by Door Contact Switch; Driver's Side
35-00 - -
01370 - Alarm triggered by Interior Monitoring
35-00 - -
00955 - Key 1
09-00 - Adaptation Limit Surpassed
01134 - Alarm Horn (H12)
76-10 - Terminal 30 missing - Intermittent

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Address 45: Inter. Monitor Labels: None
Controller: 4D0 951 177 B
Component: Innenraumueberw. D06
Coding: 00001
Shop #: WSC 00000
VCID: 28238532DBEB
1 Fault Found:
01350 - Alarm via Theft Warning System; Rear
35-00 - -

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End --------------------------------------------------------------------------------------------------

I cleared the engine codes and ran it for a few seconds while stationary, none returned, but....

It's plausible that the 01119 error is suggesting a failing F125 switch but the main obvious problem is a very rattly catalyst!

Quite busy on my road with 3 S8's together. :cool:

Also recoded barzya8's central locking module to match mine.
He had been on 15179 which didn't actually make much sense but was partly working.
Mine (and his now) is on 14315 which does what I want and appears (after testing) to do what he wants as well.

Just to clarify my code of 14315, which was arrived at after a fair bit of experimentation long ago.....
It's basically everything ON except:
4 (drivers door only with key blade),
512 (single flash confirm on radio lock),
2048 (US window logic, operation disabled with doors open) and
16384 (drivers door only with remote).

Big thanks to HPSauce for the VCDS lesson. Have already shared with David down at DS Autowerks and initial response on the misfires is a faulty air flow meter. Will update once he gets back to me with a clearer view.

Glad to be able to help. :cool: How did the car behave on the return journey?
Remember you will need to do another scan to confirm the engine problems; I don't think I cleared the codes properly before you went for a "spin" after the first scan, but I think I did after the second look but only ran the engine for a few seconds then?

You really should invest in VCDS, assuming you have a suitable laptop, as it puts you in control with so much more information. It really is essential on these cars.

Car was perfect on the way back. Behaved much better than on the way there. Yes I'm going to look into VCDS but given I'm about invest in new MAF sensor, 4x new tyres and 2x refurbished cats I'm going to leave it a week or two....

Fair enough, but make sure the MAF is tested before assuming that's a problem. With VCDS (and other tools) you can check/log the readings.

Also, if your F125 switch is playing up you can get very odd behaviour as the ECU's don't know what gear you're in.

Forum member A8L has a VCDS for sale and is about to put it on fleabay if no offers from forum members. +++

OK will do. Just out of interest how easy is it to replace the MAF? Job for the home mechanic or novice?

Changing MAF is a doddle, I've swapped mine several times while testing problems.

Bit of big air trunking and related stuff to remove, handful (or less) of screws, that's about it. And a wiring plug.

I have a spare one you could swap in on a temporary basis to see if it changes anything.