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#1
27th April 2009, 07:54 AM
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Secondary Air Injection System
Been having problems recently, VAG-COM pulls up the following:-
17831 - Secondary Air Injection System; Bank 1: Insufficient Flow P1423 - 35-00 17819 - Secondary Air Injection System; Bank 2: Insufficient Flow P1411 - 35-00 That was after I noticed the engine light on a few days back. Then this morning on my way back south, just cruising along at 75, suddenly all power cut, ABS light on, EPC light on and for the next 60 miles it wouldn't accelerate up any form of incline, only on declines and not with full power. Got to work, checked it out with VAG-COM, same code 17831 amongst others from the ABS saying problem from throttle position sensor. I think the TPS and ABS problems came as a result of driving after the 17831/17819 codes. Reading up on the codes at the Ross-Tech wiki, does anybody know where to look for this secondary air injection pump and the valves associated with it, as I'll have to check the pipes over to start with - this is the problem that has been causing the little hesitation changing gear and at about 3500-4000rpm under load I think. Any help finding the pump/valves/pipes much appreciated  Ah, found some diagrams on VagCat, no worries chaps
Last edited by DJStrange; 27th April 2009 at 08:03 AM. Reason: Found more info 
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#2
27th April 2009, 08:23 AM
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How odd....
The secondary air pump is sat in the bottom of the airbox at the front of the engine bay... Its fair to say that they are a common-ish fault. Both my S8 and RS6 delvoped faults in the system. I had the pump, and one of the valves fail, however I would say that they cars drove normally whilst the faults were present.... This severe loss of power, and involvment of the ABS system suggests theres more going on here than first meets the eye... I suspect the engine ECU may have turned off the ABS/TCS etc, but for that then it must be thinking its got something more major at fault - I guess if there were a problem with the throttle position sensor, this would be a fairly major concern causing the ECU to intentionally not to respond to full power requests....
__________________
For parts enquiries and Forum User Administration please contact customer services directly, not me  - enquiry@a8parts.co.uk, www.a8parts.co.uk, or call 01642 783537The Daily Town Car - 2023 Tesla Model Y Performance. Black with Black. Giant ipad screen, huge sunroof, 4 wheel drive, Tow bar, lots of ooomph and made in China, so actually built properly unlike the Californian ones. The Family Wagon - 2018 Tesla Model X. Black, 7 Seats, Towbar, Homelink, Enhanced Auto pilot with Summon and self park, Heated front seats, CCS Charger upgrade, MCU2 Upgrade, Falconwing Doors, Self opening / closing doors, Netflix, Spotify, toys, Air suspension, alcantara roof + lots of other stuff...... The 17 year old Driver Wagon 2015 Skoda Citigo Monte Carlo. Alloys, Power steering, Aircon, Leccy windows, Sat Nav, bluetooth, central locking, cup holders, 59 whole bhp. Million times better than my first car. Well jealous..... The First 20 Audis: 2001 D2 4.2 QS Silver, 1997 D2 S8 Silver, 1999 D2 4.2 Silver, 2002 D2 S8 Dolphin Grey, 2003 C5 RS6 Blue, 1998 D2 S8 Black, 2000 D2 4.2 QS/S8 Ming Blue, 2003 D3 4.2 Ming Blue, 2005 B7 S4 Blue, 2006 D3 3.0 Tdi Black, 1999 D2 4.2 Silver, 2003 D3 4.2 LPG Crystal Blue, 2000 D2 S8 Silver, 2007 3.0 Tdi Q7 Black, 2009 B8 S4 Black, 1998 D2 S8 Agate Grey, 2006 D3 4.2 Tdi Blue, 2006 D3 S8, 2007 Q7 3.0 Tdi, 2006 C6 S6, The Second 20 Audis: 2011 A7 Sline, 2001 A2 1.4 Tdi Black, 2002 A2 1.4 Tdi Silver, 2006 A8 4.2 Tdi Blue, 2007 4.2 Tdi Q7, 2006 S4 Cab Silver, 2010 RS6 Saloon Black  , 2007 TT Roadster, 2010 A8 D4 4.2 Silver, 2006 C6 A6 2.7 Tdi Quattro, 2000 D2 4.2 QS/S8 Ming Blue (again), 2008 Q7 4.2 Black, 2009 C6 RS6 Saloon Daytona Grey, 2001 Fully Loaded A2 Tdi, 2006 Avant S6 Black, 2007 VW Caravelle Exec Black (almost an Audi) 2009 TT Roadster Daytona, 2015 Q7 4.2 tdi lava grey, 2002 GmbH D2 demonstrator, 2006 D3 A8 LWB 4.2 Tdi Black Most Recent Audis: 2001 A2 1.4 Tdi Black, 2007 4.2 FSi Q7 ABT Blue, 2016 S5 Coupe Launch model, 2004 S4 B6 Cabriolet, 2016 Q7 Sline White, 2006 Q7 4.2 FSi Black, 2012 Q7 Sline+ 4.2Tdi White, 2008 Blue Audi S8 Everything Else 1989 Subaru Justy, 1986 Vauxhall Cartlton 2.0 GL, 1985 Vauxhall Carlton 2.2 CDi, 1987 Ford Sierra XR4x4, 1983 Vauxhall Senator, 1985 Vauxhall Senator 3.0i, 1997 Polo Saloon, 1997 Peugeot 306 1.9 TDi, Ford Sierra Sapphire 2000E, 1990 Subaru Justy, 2000 Subaru Impreza, 2000 Subaru Impreza RB5, 1993 Range Rover LSE, 2005 VW Bora, 2003 Skoda Superb, 2003 VW Passat V6 4 Motion, 1996 Peugeot 106, 2000 Range Rover 4.0, 2019 Tesla Model 3 Performance
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#3
27th April 2009, 08:27 AM
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I replaced the throttle position sensor on my S8 and made a massive difference to the drive.
A problem on the slightly higher mileage cars is that an engine breather chucks oil through the throttle body and gums it up. I removed the throttle body (Quite straightforward without removing the inlet) and stripped it and cleaned it. I also relocated the engine breather pipe to stop it being gummed up in the future. Car drove miles better afterwards.
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#4
27th April 2009, 08:56 AM
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Well when the engine light came on, I was just driving gently to the shops for lunch, probably no more than 45mph. Nothing happened, I just happened to notice the light was on, so I checked it with VAG-COM and only got the two air injection faults. Thought nothing of it at the time, no running problems or anything, so cleared the DTCs and everything has been fine.
Drove home that night, no problems. Headed north on friday, no problems again. Drove for about 110 miles this morning, no problems at all then suddenly this loss of power. I was in cruise control, 75mph. The only thing I can think is that the fault caused a hiccup in power which triggered the ABS which perhaps misread the throttle position due to it being in cruise? Dunno, scratching my head, but this is the fault read out from this morning and the engine had not been switched off since the fault occurred:- Engine: 17831 - Secondary Air Injection System; Bank 1: Insufficient Flow P1423... 18047 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal Readiness: 0010 1101 ABS Brakes: 18264 - Throttle Potentiometer (G69): Error Message from ECU P1856 - 35-00 I'm pretty sure this is connected to the very intermittent problem that occurs at about 3500 to 4000rpm under load when there's a slight hiccup, almost like it's thinking of changing down a gear or something. I've been driving it like a grandma for a few weeks now, frightened something else expensive is gonna break on this gearbox, but now I'm starting to think the real problem is revealing itself. Once these problems are ironed out and it's had a bit of TLC on a few scratches and chips, I think I'll be parting with it anyway as I (and my wallet) have had quite enough of 8 ownership 
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#6
27th April 2009, 09:20 AM
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Cheers Doc & Ian BTW, I'll start having a look around the pipes first - I found PaulW's posts about chasing these pipes and doing the VAG-COM output tests, so I'll do the easy stuff first and then if there's still a problem I'll have a go at the output tests and report back.
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#7
1st May 2009, 10:31 AM
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Found the problem(s).
Part number 4 in the pic, like a little rod-operated bellows thingy, the rod's mounting clip on the rubber bellows has snapped. Any ideas where the hell I'll get one of these from? Also pipes are crumbling in my fingers, so I'll have a bit of a replacing session with it all. Going to look at a new motor tomorrow... more details soon - my S8 will be up for sale soon, once these last few niggles have been sorted. Last edited by Conan_the_Librarian; 1st May 2009 at 01:29 PM. Reason: add Picture
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#8
1st May 2009, 01:30 PM
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__________________
Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light.
Last edited by Conan_the_Librarian; 5th May 2009 at 04:25 PM.
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#9
5th May 2009, 02:41 PM
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Not sure if the guys at A8P will be ok with this information - please remove if not acceptable, just trying to help others if they get stuck like I have (I'm towing my caravan back north in a week's time so this is getting rather urgent).
Well, interesting development here - the guys at A8P didn't have any unfortunately, so I went on the hunt and found some interesting things for anyone who has this particular problem. Rang Audi Amersham, spoke to parts, gave him the part number off vagcat (077198327A - repair kit for adjuster), he gave me a price, I fell off my chair...  Asked him what the kit contained, he asked a technician who said there were two bellows things and some linkages, £147.80 inc. I said my thankyou's and went online to hunt. First of all I put the Audi part number into google, found this http://forums.audiworld.com/showthread.php?p=15582059 which sort of explains pretty much what I'm experiencing - lack of power when it hits a certain point in the rev range. The bellows units are made by Hella (part no. 004 538), so I put that into google and found these http://cgi.ebay.com/ebaymotors/1985-...31010008r16443 Hmm, very interesting. Needless to say, I did some more hunting and tracked down the exact same part as the audi one on ebay albeit without the linkage bar for less than 20% of the price audi quoted. Range Rovers use it on the cruise control too (part no. ETC7150). I'm happy this repair for once hasn't cost me £100+ I'll update if the part works when it arrives. Last edited by DJStrange; 5th May 2009 at 03:01 PM.
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#10
5th May 2009, 05:14 PM
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Quote:
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Linear Mode
