After all the work, treated the car to a detail
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Replaced the Start Stop button, worked fine but annoying when they wear
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Super simple 10 minute job, remove the ashtray, then removed the torx screw behind it as shown
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Once the screw is out pull the ash tray frame out and disconnect the electrical connection. Then you can just pull the center console trim up and forward to remove.
Replacing the switch is straight forward, 1 torx and a small brass pin, sorry I didn’t take a pic of that, but it is obvious
So my front right (2 year old 40-50k Arnott) strut seems to still be leaking as its seems to be dropping. Checked the valve block and I can see anything, so it looks like that needs replacing.
WOW good to know it was that simple. Also thanks for the pictures I’m sure that will be useful in the future.
Sorry my bad typing on an iPad , I can’t see anything on the valve block, so I’m looking at replacing the strut
Well my suspension woes seem far from over, I have the following:
- Slight knock developing on the LHS, quickly checked everything last night and nothing is loose. So I think it may be the Arnott strut I fitted, will call them today.
- RHS front and rear has started dropping, rear 5-8mm and front 25mm overnight. Rear is the original and front is a 2yr old 40+k Arnott.
- Keep getting a repeated G291 code.
Whilst the previous owner replaced both the valve block and the compressor, I only have records that it was fitted by Audi and the PO had supplied the parts, so unsure what they fitted.
I have ordered a compressor rebuild kit, looks like most G291 code relate to weak compressors. My concern is the dropping RHS is linked to the valve block more so than the struts, done the soapy water and it’s not showing anything.
Think I’m going to order a new Arnott front right strut, get that done and see what breaks next 
Thought I would give the latest update, slowly knocking down the issues
Regarding the knock, I checked all the suspension linkages out and whilst they were torqued up correctly on assembly, the upper control arm (left) pinch bolt just nipped up a little more when I re-torqued it maybe 1/4 - 1/2 a turn max. To be honest I wasn’t totally comfortable that the bolts that came with the Mearle control arms were up to spec, so I purchased replacements from Audi, fitted and torqued to spec and that seems to have resolved the clunk. I think the parts just settled and needed a re-torque or the bolts relaxed, as the clunks started maybe 800 miles after the initial rebuild. I am surprised by this as having done suspension work before I haven’t had this issue, but glad it is resolved.
On the front end dropping, after doing some reading and positing on Audiworld, it seems the correct procedure to check the struts is to put the car in Jack mode (it stops the car from adjusting the ride height when parked, and eliminates the solenoid valve from what I understand) then measuring the drop as an accurate measure of the struts leaking. So I did this and the front was dropping 20-25mm in 24hrs, more so on the RHS which was the older strut (LHS just replaced). So I disconnected the sway bar to ensure the front drop is independent of each side, re set the car and the RHS front was dropping over 30-40mm in 24hrs.
Purchased a remanufactured Arnott for the RHS front, fitted it and left the car in Jack mode for 10 days and the car dropped 2-5mm across all corners, bearing in mind my measuring wasn’t totally scientific (tape measure by eye from the floor) and that the temp dropped around 20 degrees over that time I felt that was fine and acceptable. So based on this I really don’t think I have a leaking strut issue anymore. So all seemed fixed……….
Onto the G291 code, this code relates to a sensor in the valve block, some posts seem to link this code to a weak compressor. I have checked the lines to the compressor, valve block and struts and there are no visible leaks with the bubble test. And based on the above I’m confident my struts are good. On the compressor side as noted in previous posts the previous owner supplied a replacement one that was fitted by Audi last year, and I noted that after fitting the new RHS strut when I restarted the car it pumped the system up quickly and the compressor doesn’t run very long at all, mostly the car seems to be able to pump itself up from the accumulator. Based on those data points I feel the compressor is ok.
BUT, my problem is that I am still getting the G291 code, despite clearing it repeatedly, I was to the point that the car seemed fine and I was going to ignore it, until………….
Last night after parking the car a few hrs later the front right had dropped again ARRRRRRGGHHH, opening the drivers door and you can hear the valve block cycling and the car pumps itself back up again from the accumulator, no compressor running. Checked again this morning and the front right has dropped and the G291 is pretty much showing every time I drive the car. So I’m to the point where I am pretty sure my valve block is failing of has a sticking valve as the drop is random, and when it does drop it is severe. With the new struts I’m confident they are good, I do think I had a strut issue as in Jack mode the car was dropping.
I have an Audi used part specialist close to me and they have a used block for $139 and the guarantee the parts are tested, I’m going to get that and see if I can resolve this G291 code first, then check whether this random dropping is resolved. Looking on the bright side by the time I have finished this car will have a fully rebuilt suspension system, thank god I’m not paying a garage for labor.
Whilst I have the car parked up for the above suspension work I decided to replace the front brakes, the pads were pretty much down to the sensors, yet the discs still had plenty of material on them.
I ordered a set of Pagids off Rockauto, I have them on my BMW 328 and they work great. I thought the price was really good at $105 delivered. And the fact they come with the sensors built in meant the front pad replacement on the S8 is cheaper than a run of the mill BMW 328!!.
Dropped the discs off to a local garage for refinishing, they were shocked at the size of them as they mostly work on domestic cars. $27 later and they were perfect and ready to fit. It’s a really easy job to do and it take longer to jack the are up and remove the wheels than it does to change the brakes.
So for $132 I essentially have new discs and pads fitted, I almost want to call Audi to ask what they would charge as clearly they wouldn’t refinish discs and I am sure would fit new.
Audi policy is to obviously replace the rotors. dealer rotors are not cheap so that is a big chunk of the cost. add the S8 with carbon brakes and its a lot of money on a brake job.
The initial good news seems to be that the replacement solenoid valve block seems to have resolved the G291 fault code. Before it came up pretty much every time I drove the car. Drove it a few times today and nothing, fingers crossed.
Following doing the front discs and pads I wanted to also do a brake flush. I have a Motive Power pressure bleeder, best brake investment made. Makes one person brake bleeding simple and way faster.
I put 2 quarts through the system, and this came out of the rear brakes
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The bleed nipples we almost seized tight on the rear, I get the distinct feeling its been a while since the rears were flushed.
Fronts were better, but happy to know they full system is done now.
man, the fluid was DONE. (sigh) I guess I need to do mine…Just so tedious without a pressure bleeder and an extra person. I’ve been dragging my feet on doing my brakes period - my front rotors are done. I want the JHM LW rotors, but after ponying up $2k for a new intake my spousal approved budget for the year is shot.
Any plans for the car other than fixing the list of gremlins?
Not really any plans to modify it, other than a little more noise. So thinking about possibly removing the rear resonators, or opening up the rear muffler to see if you can gut the a little for noise.
Working on an annoying noise in the car since buying it, sounds like a pebble rolling inside the passenger rear door when you really get on and off the gas. After removing both front and rear door cards, nothing there.
Tracked it down to the door sill chassis rail. It looks like the sill trim was removed previously and the clips that fix the trim snapped off and now rolling up and down the chassis. You cannot see inside or get access to remove it. I dropped some clear silicon down the clip hole, drove the car and caught part of the clip. Leaving the silicon to harden and hopefully trap the roaming clip. Fingers crossed that will stop the rattling, as it is bloody annoying.
So some good news on the car, ran a VCDS and the G291 suspension code is gone for good. I think its the first time since owning the car that I haven’t had some sort of suspension code.
Also the silicon in the frame rail seems to have addressed the annoying rattling trim.
Still have a few outstanding items:
- VCDS codes for the Alarm horn (Which is odd as it works when I set the alarm off)
- Code for the rear right footwell heater, seems a common issue. Not something that really bothers me day to day.
- TPMS sensors out, again another one that doesn’t bother me as I switched the warning off. Will replace them when I get new tires.
- Trunk opens on the 2nd try, first try lifts the RHS first then stops, 2nd try opens it. Anyone had any luck adjusting the hinges to fix this?
- Seeing what I would call excessive condensations in the headlights usually after a car wash, it drys but its annoying. Will have to look into this more.
- Still have some maintenance that I want to address - new fuel pump, wipers, tranny/diff oil changes.
Other than the maintenance I could ignore all of the above, but enjoy working on the car so unless a big $$ fix will probably address sooner or later. When they are running well they are great cars 
Is it hard to DIY for the headlights?
It’s very easy just takes time. Hardest part is taking the bumper cover off if you want to remove the headlights. You could do it with them fitted but it’s a little messy.
The actual sanding just takes time to go from 800 to 5000, probably 30 minutes a light. Polishing with an orbital is simple, then sealing is simple just wait an hr between coats.
Very satisfying once it’s done and your lights look like new
Headlights look great. Nice to see the car is comming along.
I did the toothpaste trick with my headlights and it wasnt quite as sharp as yours but you are right it does make you feel much better and it is something most people can do on there own.
A brief update, I haven’t had much of a chance to drive the car lately. But have put on 2,000 miles since the last round of work I did on it.
I get it on the lift and had a look around it and please to say no more oil leaks which was one of my concerns that it was leaking from ore areas than just the oil filter housing. Been close to 3,000 since that repair.
Also ran a diagnostic and no suspension G291 codes, looks like the valve block finally fixed that one.
Car is running great, averages 16mpg which I don’t think is so bad for such a monster engine.
Looking forward to the weather warming up here in MN so that I can look into a few minor issues, be interested if anyone has any feedback on these:
- Front suspension creaks a bit when the weather is really cold below 0F, seems to be a common fault with A8’s. Many post that is the suspension arms to the hood seal. So I will be looking onto that.
- Front LH headlight has bad condensation after I wash the car, RH has it a bit but not that bad. I need to pull the bumper to investigate further but it does seem to be a common A8 issue.
- Whilst I am into the lights I want to look at getting some better main beam bulbs as for a 10yr old car they are not great. As it looks like its easier to change them with the lights out of the car as there isn’t much room with them in situ.
- Again whilst the bumper is off I’ll replace the suspension compressor sealing ring and look at the mounting rubbers as I can feel the vibration from mine when it runs occasionally.
Be interested in anyone has any experience and fixes for the headlight issues, be nice to have brighter/dryer headlights
Update: Just rolled over the 100k mark last week, glad to say it was completely uneventful!
Did some work on the car this weekend to address a few of my minor gripes, sorry to say that I didn’t take any pics of the work.
When I purchased the car I noticed that the LHS front inner fender trim did not fit inside the fender lip, so water would get through the gap in the area to the compressor, I thought it was just bad fitment, but with age and maybe some botched repairs I couldn’t get it to fit correctly so purchased a new one $120 from ECS. I expect this gap/fitment issue didn’t help with my headlight fogging as clearly water could be splashed behind the light area. Especially when I put the car through touchless car washes here in MN every few days to wash off the salt. I also cut a section out of the old LH one to repair a hole in the RH, looked like the car was driven without the liners being properly fitted and they had some tire rub that wore through the liner.
Headlights - whilst I love driving the car the performance of the headlights at night left a lot to be desired. The output was weak in both low and high beams. I had read that older xenon bulbs degrade, so decided to replace them. Whilst there I also wanted to try and fix the condensation issue that I have. I don’t think that there is any way you can get to the bulbs from inside the hood, and I would suggest its still pretty tough getting to them from the wheel fender liners. As I wanted to give them a good check over, I went the whole hog and removed them. To be honest it’s not that difficult to remove the front bumper and it made it way easier to work on the lights on my bench.
Be very careful taking the back off the lights, with the heat and age the plastic cover locking tabs get very brittle and can easily be broken. With the back off I ran a hairdryer through the lights for a few minutes to completely dry they out. Replaced the bulbs with Osram 66240NB Xenarc D2S Nightbreakers, $99 off Amazon. I couldn’t see any damage to the light cases that would allow water in, but the overall design and aging plastics cannot be completely water/vapor tight. I cleaned the seals of the bulb covers and added copious amount of petroleum jelly in an attempt to help them seal.
With the bumper off I decided to refurb the compressor, I don’t have any codes off it pointing to issues, however I don’t know how old it is and I do notice when it was running I feel vibrations through the car. Removing it is easy with the bumper off, I noticed that during the previous repair (by Audi) that 2 of the bolts securing the compressor were stripped. With the compressor out I replaced the piston sealing ring, they run around $30 off Ebay. Mine showed some signs of wear but it wasn’t terrible. I also replaced the compressor isolation rubbers and mounts $93 from ECS. The compressor was mounted with what looked like a mix of bolts/washers and rubbers, again a supposed Audi repair. The new mounts let the compressor float more than the previous installation. Refitting it, replacing the stripped bolts and ensuring cables and lines didn’t touch the compressor to isolate the vibrations.
Whilst under the car I also greased the sway bar to chassis mounts, some suggest that with age these cause the squeak/groan in the suspension that I seem to get when it’s really cold. Time and weather will tell if that is the fix.
Put the car back together and ran it a few miles last night. First surprise the that the Osram bulbs are a massive improvement, obviously I can’t compare new Audi bulbs to them so maybe replacing the bulbs with Audi parts would also have an improvement. I was really happily surprised, they illuminate the road now as well and my wife’s 2017 Grand Cherokee. Where before they were defiantly a weak area, to the point where I was thinking I might sell the car and get something else. Living in MN with the long winters means you need good lights, and with these new bulbs I’m glad to say I now have them. I’d suggest swapping them out ever 4-5yrs, as the brightness seems to diminished with age, other than the PITA to change them it’s a cheap improvement I’d recommend everyone does.
Also pleased with the compressor rebuild, as I haven’t noticed it running now, so the new mounts seems to have addressed the vibration.
Finally took the car through a car wash and I don’t seem to have any condensation in the lights, I think a mix of replacing/repairing the fender liners to seal properly, and having a better seal on the bulb covers may have addressed the issue. I noticed last night when I did the final adjustment of the lights (after the car wash) that the 2 adjusters had some water pooled on top. These are known to leak through the O’rings, I couldn’t see how to remove these to replace the O’rings and didn’t want to risk breaking them. I’ll leave them to completely dry out and will smear some silicon to seal them as a belt and braces measure.
Not sure what’s next on the list!, the trunk twist that means I need to hit the opening button twice to get it to open is my next job.
Just read this update. Looks like you’ve had your hands full.
Where in MN are you? I head down from Winnipeg to Minneapolis for Cars & Coffee a few times a year. Know quite a few of the Eurowerks guys.