Fontain Motors – Audi S4 Buyer’s Guide

Fontain Motors – Audi S4 Buyer’s Guide
Buyers Guides

Intro to the buyers guide:

Fontain has been Specialising in Audis since 1995, sharing the information we learn along the way. We have put this series of written and video buyers guides together, as we believe buying carefully helps you get the best value car when buying.

Being an informed buyer helps avoid unexpected costs and plan future maintenance!

For the full video form of this S4 buyers guide, check out our YouTube channel or Facebook page. @fontainmotors


This is the newest in our buying guide series of videos, with a little bit of a difference. We’re talking about the 2003/2007 S4 B6 and B7 generation cars. Not just how to buy one, but also why you should buy one and why you should buy one today. If you’re in the market for a fun Audi, a lot of the obvious candidates today have got a little bit out of reach.

If you want the first car everyone goes for, a B7 RS4, for a really good one you’ll probably need £20,000 or more today. If you want an R8 / RS2 they’re £40,000. Prices are higher than they were a couple years ago, they have probably got further to climb as well.

Then you get into the maintenance of cars like that, where they have some pretty exotic components, sometimes difficult to get. Brakes are expensive, tyres are expensive and bespoke suspension bits cost a lot of money.

This little beast behind us (S4) gives you probably 80% of a B7 RS4, for an absolute maximum of half the price. They’re a little bit of an unsung hero, a bit of a bargain.

Now really is the time to buy one, before everybody else realises quite how good they are and quite what good value they represent.

B6 / B7 S4 Overview:

The B6 and B7 generation S4 were an amazing engine with a very useful and practical car wrapped around them.

You simply don’t get, with the modern small turbo engines as good as they are, the soul, the noise, the personality of a traditional normally aspirated V8. That’s exactly what you get with an S4. They’re also very usable, in that if you pick an estate car, there’s no reason you can’t use it everyday for family stuff. The saloons look great and the convertibles are wonderful for summer.

Certainly, buying one isn’t without its risks, but the faults of these cars are very well documented. The support community around them is first-rate and a lot of the things that you read or watch on YouTube or see in the magazines and the forums, about the horror stories, are exaggerated.

They really aren’t as bad as some people would have you believe. Factor in the fact these purchase prices are very low. The risk is mitigated as you can have a really exceptional one for £10,000 as an absolute maximum.

Audi launched the B6 generation S4 in 2003. Initially it was available with a saloon body style or an estate. The convertible came on a short while later. Again at launch it was a 6-speed manual, with the introduction soon afterwards of the 6-speed tiptronic automatic transmission

In 2004, for the 2005 model year, the car got a facelift, that’s known as the B7 generation. The body styles continued; saloon, avant and convertible. The gearboxes continued as well. 6-speed manual or 6-speed tiptronic and they were available through to the end 2007.

All B6 and B7 generation S4s use the same normally aspirated 4.2 L V8, a chain driven 40 valve unit, 5 valves per cylinder, as Audi were using a lot of at the time. They all produce the same quoted output of 344 PS or metric horsepower, which coincidentally is exactly one PS more than a contemporary BMW M3 made. A cynic would say Audi did that on purpose…


Throughout production there was the choice of a 6-speed manual, the standard unit, or 6-speed ZF torque converter automatic. The four wheel drive system is slightly changed for the B7 facelift car, where it got the newer version of the Torsen four-wheel drive system that altered it from a 60/40 front to rear torque bias, to a 40/60 front to rear torque bias.

All cars have permanent full-time Quattro four-wheel drive.

As standard what did Audi include? As with a lot of German cars at the time, not a great deal unfortunately. The B6 car on its standard kit, got you 18-inch alloy wheels, electric Recaro seats in the hard top cars or electric sports seats in a convertible. Plus, Xenon headlights and half leather, everything else was an optional extra.

B7 didn’t change a great deal in terms of standard equipment, still half leather although you got Bi-Xenon headlights, rather than just on the dipped beam in the earlier car. The slightly revised four-wheel drive system mentioned earlier, but other than that it was the same. Electric seats, Xenon headlights ,18-inch wheels and half leather.

B7 vs. B6:

So what makes a B7 different to a B6? We’ve touched on a few of the differences already, but the big ones are all cosmetic. Audi changed the front end styling of the car quite significantly to the single frame grill type, which most of the range changed to at that time.

New lights, new grills, new bumpers. It was the same story at the back of the car, with a restyled rear-end, new tail lights and B7 generation cars also moved to the quad exit exhausts, that every S car had had since then.

Desirable Options:

What did buyers look for at the time? What do buyers look for now? What’s popular? What’s nice to have?

The palette of colours really hasn’t changed a massive amount, it’s quite personal. What you like is what you like. There were probably more reds sold than there are today, but if you fancy something fairly modern, a black or grey or blue, they’re not difficult to find.

In terms of interior colours, you got either black or Lunar Silver, which is a sort of an off-white magnolia shade, and half leather was standard. You could also have half alcantara in a two-tone effect if you wanted, or a full leather interior. Again personal preference, the leather tends to wear pretty well, the alcantara can bobble very slightly. But unless it’s really bad, you can generally bring it back to looking nice, with the same bubble gun you use on your jumper.

Goodies and gadgets! As we discussed, the standard kit list was quite short. The things that you’d want today are really the same things people wanted when they were new. It’s nice to have the auto lights and wipers, parking sensors and cruise control. Heated seats were not standard in S cars then as they are now, and they’re well worth having.

The satellite navigation still works and looks great, although it’s a dated system, it definitely is the nicest looking stereo in the dashboard. Bose speakers are worth having. And there were various other small options as well things like memory seats although, they’re not that common, they’re easy to find these days.


There was no factory sport option for either a B6 or B7 S4. The standard system sounds quite nice, but a lot of buyers at the time, and now, wanted to hear a little bit more of what is a really beautiful sounding engine.

At the time the cars were new, and now for that fact, Milltek is the brand that you’ll see come up and probably the most often. They make lovely sound systems.

If you’re looking at a car that’s already fitted with an aftermarket exhaust, do ask what it is. Because, a lot of people selling them offered a non resonated system. Which is basically a straight through exhaust with a deleted centre section. They drone and blair and are really not nice at speed. Make sure you can live with it, if you want a properly loud one.

We far prefer the systems that retain the centre resonator section but just let that V8 sing a little bit more, letting you hear it to the fullest.

What goes wrong with S4s?:

Let’s deal with the elephant in the room, and what everyone on every forum tells you is absolutely guaranteed to ruin your day and cause a remortgage…the timing chain. A Lot of what you’re going to read about this is wrong. Straight up, if your car needs its timing chain guides replaced, today it’ll cost you here about £3000.

Again as we talked about earlier, if you hold in mind that these cars can really be bought quite cheaply, even if you need to pay for a timing chain, you’re still in for not even half what an RS4 costs. Compare that to putting brake discs on a B7 RS4, you are talking £2,500 for that alone.

All S4s B6 B7 Generations, although affecting the earlier cars morso than later ones, the timing chains can suffer issues when you cold start the engine. It is normal to hear, just for one or two seconds, a very slight rattle from the timing chains, as oil pressure builds up and tautens the chain.

If that rattle is excessive, Ie. is more than one or two seconds, or it’s loud or it carries on, or you’re hearing rattling when the engine is running, if the timing is out, you’re getting engine lights and faults around that, it generally speaking points to the timing chain.

When we renew them, we change the chain and the guides. There is one guide in particular that is notorious for breaking, even Audi knows about this one and later V8s, like in the RS4, they use a metal guide rather than plastic one in the B6 S4. They fit absolutely fine, and once you’ve got your new chain and guides installed, it’s fixed! You’re also adding a good chunk of value to the car.

The convertible tops:

So if you’re looking at an S4 cabriolet, all cabriolets have a fully electric roof. They can suffer some problems, but they are not generally horrible to fix. A Lot of the time these cars are quite lightly used, somebody may not even drive them at all through the winter months. They then go to start the car up in the spring, but the battery is completely dead. Just pop a new battery in or charge the old one and the roof does something funny.

It may open halfway or not close or just flashup errors on the dashboard. If it is just battery related, very often they can simply be recoded, and they come back to life absolutely fine. So if you’re not using it through the winter, think about a trickle charger.

Apart from that, the micro switches, the little sensors that tell the car what position the roof is in, can go wrong but they’re inexpensive.

If the roof has a more serious problem, it is mechanically not working, for example. The motor that drives the pump, the motor itself is the most common failure and is inexpensive. If the pump has failed there’s no need to buy a new one, because they are expensive, they can be rebuilt.

The actual fabric of the roof itself is generally very good quality. You will see some slight furring of fabric on the folds of the roof, it shouldn’t be excessive and in extreme cases something like a rip or tear, there are companies now who supply really good quality aftermarket replacement tops.

One other thing with the roof, it’s actually in the boot. The soft top storage box that folds down when the roof falls down, if someone shoved a box or bag into the boot that’s far too big, the storage box that drops down to make room for the folded roof can break. So if you’re looking at an S4 cabriolet, have a look at the storage box in the boot to make sure it works.

Body work and interior:

Generally they’re pretty good. The B6 / B7 generations of A4, have got a well-earned reputation for being pretty tough and cosmetically no different. Outside the car, and you’ve got to remember that the youngest of these now is 14 years old, you really should just be talking about cosmetic wear and tear, rather than actual problems. Obviously, have a good look around the car, any vehicle of that age is not going to look like it’s brand new, but you want to make sure that it is pretty good, and any repair work has been done for cosmetic reasons, not covering accident damage.

Corrosion shouldn’t really be an issue, and if you are seeing rusty bubbles, look really carefully as it might be pointing to signs of poor repair work or cheap aftermarket panels.

Interior of the car, they stand up pretty nicely, unless an owner has been horrible to a car or it’s done loads of miles, the surfaces wear fairly well. You can see some marking on soft-touch surfaces like the door handles, some light scuffing on seat bolsters happens.

If a car’s got alcantara, you can sometimes see that bobbling which can normally be sorted easily. Two complaints that any A4 owner will tell you tales of, the armrest break and the glove box door break. They just do, but they are not expensive parts.

Leaks, oil and coolant:

S4s leak both of those things sometimes. Most common oil leak is probably the cam cover gaskets. They get old, gaskets dry out, they leak a bit of oil. If they’ve been left unchecked and are leaking a bit more, you can get some oil on the exhaust manifolds, which you’ll know about because it smells like burning oil, and not too bad to sort. If you were having an engine out to do the timing chains it’s an easy and sensible thing to do at the same time.

Coolant leaks, most commonly both generations of car use two small auxiliary side radiators. The bottoms of these radiators corrode, bulge and will leak. Again it’s not too bad to replace, it’s just a bumper off job.

Whilst we’re on the subject of oil, Audi’s V8 does like to burn some. Officially they can consume up to half a litre in 1000 km. Keep an eye on it, check it once a week. Particularly so if you do more miles or using the car quite hard. It’s completely normal, they use some oil, they always have done. We find that switching from the standard 5-30 grade of oil, to a 5-40 can improve this as well.

Knocks and creaks:

Behaviour like most Audi multi-link suspension setup, a number of bushes, joints, ball joints are now at least 14 years old, and a lot of them have done over 100,000 miles. They might not be bad enough that year that the MOT tester is going to flag them as an advisory or a fail item. But they do soften and wear with age and they do spoil the way the car drives.

Top arms are particular culprits, but these are pretty much standard A4 parts. None of them are particularly expensive, you can do a really thorough overhaul of the suspension for not a lot of money and have the car handling exactly like it’s supposed to.

RNS-E Navigation:

So from about the middle of 2004 through the end production the RNS-E DVD sat nav option was quite popular. They do have their problems, they are fixable. It’s very common to see an error popping up on the screen, or the car complaining that it can’t read the disc.

Sometimes you get lucky and cleaning the laser will bring some life back out of it. But more often than not, the laser itself is worn or has failed, but new ones are available.

If you’re seeing other errors popping up on the screen or the units not working at all, it can be the motherboard has failed. Again replacements are available. Lastly, the screens from the factory have an anti-glare coating that is quite easy to scratch. If someone’s been careless cleaning it at any point, the coating can come off. You can simply polish it so coatings are gone, but the screen is then quite shiny afterwards. But again replacement screens are available.

Air Conditioning:

Make sure it works! If the system is regularly used, occasionally serviced, ideally left running all year round in your automatic setting, it shouldn’t give you any trouble. It is worth testing it thoroughly to make sure it’s behaving as if it was left unchecked, or if you have a compressor failure, there’s quite a lot of labour involved in getting to it, to replace the compressor itself.

Clutch and Flywheel:

Clutch and flywheel, regarding manual cars. These are powerful four-wheel drive cars, the clutch is the weak link in the driveline, but for good reason. It’s a damn sight cheaper to replace the clutch, than replace a differential or a gearbox. They last fairly well, they are generally up to the power but they don’t last forever. Particularly if a car is driven hard or even driven carlesly. They’re reasonably expensive to replace but not insurmountable, and there’s no reason they can’t last over 100,000 miles, if they are used with a little bit of care and respect.

The Ignition Switch:

If your S4 is sometimes a little bit recalcitrant, doesn’t do all this told when you turn the key, or even when you take the key out it doesn’t do what you expected to do, and the lights stay on or the stereo stays on, it can point to a failed or failing ignition switch. This is more common in period than it is now, in that Audi did revise the part, and once replaced with the later to go wrong again.

Overall parts availability for B6 / B7 generation S4s is excellent, it’s really really good. Most stuff is still available from Audi.

Being an older model, some things are discontinued, you might need to order an older piece of trim, things like that they don’t bother stocking anymore because they haven’t sold the cars in 15 years. However eBay, forums, owners groups, availability of used parts for all A4s of this age is first-rate, and most stuff is really cheap when it comes to things like consumables and suspension components, most of it still available from Audi. But you can also buy, really good quality aftermarket parts for a lot less than Audi charge you for what’s often exactly the same bit in a different box.

General maintenance:

Starting with simple stuff. Oil servicing, every 12 months, no more than 12,000 miles if you are using the car more, but a lot of owners these days don’t use them anything like that much, so stick to 12 months.

We also recommend using 5W 40 oil, rather than the 5W 30. Regular oil changing is really important for the health of the engine and also using the 40 grade reduces the amount of oil that they burn.

Inspection service, after 2 years, or again for higher mileage users, no more than 20,000 miles. So you are going oil, oil and inspection, oil, oil and inspection, so rolling on from there.

Spark plugs and air filters. The factory maintenance table shows a 60,000 mile interval, but if you look at the spark plug that comes out of an S4 after 60,000 miles they’re clearly not so happy. We would say, stick to a shorter interval, like the newer V8s have, no more than 40,000 miles or 6 years.

Same for the air filter, after 60,000 miles they look pretty grubby, so change them a bit sooner than that. Brake fluid, 2 years again and pollen filters are the same, a 2 year interval.

Gearbox oil for the 6 speed tiptronic, the factory maintenance table shows that as a sealed for life unit, not requiring any maintenance. These cars are a little bit older now, worth taking care of them and a little bit of preventative maintenance here is probably a good idea.

If your automatic S4 is on its original oil or you don’t know if it has ever been changed, particularly if it’s something you’re thinking of keeping for a good while, getting an oil change done on the gearbox can be a good idea.


Thanks very much for reading our buyers guide!

If you have found it useful or it has inspired you to take a look at an S4, they are really wonderful cars. You need not invest a huge amount of money to get something that has character and personality in spades.

You will never get bored of the exhaust note and there is no reason you can’t use them every day if you want to.

They really are the perfect antidote to a world of downsizing, hybridisation, EVs. It’s something you don’t get anymore and you won’t see them again.

Now is the time to have one, because they are a fantastic bargain. You can get an exceptional one for £10,000. You could buy a pretty sound example needing a little bit of work, then bring it up to a really good standard, thus adding value to the car and still coming in at under £10,000.

You even see good cars coming up at £5000, £6000 and £7000. It’s an awful lot of car for the money, we remember them very fondly. We think they’re going to make a resurgence and you never know, their values, as people go out looking for V8s before they’re all gone, they may well even increase a little bit. Like with what you have seen from the obvious candidates, such as RS2s, RS4s.

If this buyer’s guide has been helpful, give it a share. If you’re thinking of buying an S4, selling an S4 or you need some assistance in maintaining your own, we would love to hear from you.

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Fontain - 25 Years of Audi