11 Most Common Audi S4 Problems (Explained)

The Audi S4 is a popular choice among enthusiasts who want a blend of performance, luxury and practicality.

It’s much more exciting than the regular A4 sports sedan, but is still a very versatile daily driver that offers loads of comfort and lots of grip in any condition thanks to its standard Quattro all-wheel drive system.

In this article, we’ll take a closer look at the Audi S4’s common issues and their solutions.

1. Dual-Clutch Transmission Issues

The dual-clutch transmission, also known as S-tronic or DSG (Direct Shift Gearbox), of the 2010 to 2012 B8 Audi S4, as well as early B8.5 models from 2013 are quite prone to mechatronic failures.

The mechatronic unit is the electro-mechanical part that controls the shifting of the semi-automatic dual-clutch gearbox.

Common symptoms of a faulty mechatronic unit include:

• Rough/hard shifting
• Jerky acceleration at low speed
• Won’t shift into reverse
• Shifts into neutral
• Hesitation to accelerate

Older models and the B9 S4 have a traditional automatic transmission.

Here’s how a few S4 owners on AudiWorld.com described their experience:

“I found a really good deal on a 2010 DSG right under 35k miles (and i forgot about the dsg issues). After a week of driving my newly purchased vehicle, I’ve been noticing the symptoms of a dying Mech Unit (bang/jerk to stop, shifting from Drive to Reverse) etc.”

“Yesterday morning on the way to the Audi dealership for an oil change my 2011 S4’s DSG ate itself. TPMS warning DSG failure, you may continue….etc. within a couple of miles it came to a complete stop. Towed in, this morning the shop calls and….$12000 for a new transmission, both clutches slipped, metal shavings in the transmission. 71,000 miles, car looks and, well, did drive like new, never abused, only one MINOR issue during warranty period, always serviced by Audi.”

Another owner on Audizine.com had this to say:

“12 S4 with Mechatronic Unit issue and no warranty. I’ve had the car for almost 2 years and it just reached 70k on the odometer. Recently it threw the “gearbox malfunction, you may continue driving” code. Took it to an indy shop in North NJ and they said that there’s an issue with some harness in the mechatronic unit. It will cost about $1500 to fix (parts and labor).” 

The S-tronic transmission has to be serviced with new fluid every 40,000 miles if you want to avoid premature failures.

That said, the mechatronic unit in the pre-facelift B8 cars can still eventually fail even if they were properly maintained.

If the transmission is already having problems, a fluid and filter change might be able to get rid of the issues.

There are also mechatronic repair kits that cost around $800 that can sometimes fix the gearbox issues.

Replacing the entire mechatronic unit can cost around $2,000 to $3,000. If you need a new transmission, it can easily cost you over $5,000.  

2. Coolant Leaks

Coolant leaks due to cracked water pumps and thermostat housings are a very common problem on the B8, B8.5 and B9 generations of the Audi S4.

The water pump and thermostat housing, as well as a lot of pipes and fittings, are made out of plastic that get brittle and crack over time.

Common symptoms of coolant leaks include:

• Low coolant warning
• Empty coolant reservoir
• Visible coolant leaks
• Smell of burnt coolant
• Overheating issues
• Heater doesn’t work

The auxiliary radiator of the B6 and B7 models from 2004 to 2009 is also notorious for developing leaks. 

Here’s how a couple of S4 owners described their experience on Audizine.com

“I have a 2011 Audi S4. Coolant has been leaking for the last month or two and recently it goes from MAX to MIN very quickly (within seconds to a minute) upon topping it off, but then it stops leaking as fast and becomes drivable for at least half a day or so. My mechanic took a look and is pretty sure it’s the water pump. He is charging $1886 ($473 parts, $517 body labor, $356 mechanical labor, $396 body supplies) for what appears to be replacing the water pump (with a new german metal based one rather than OEM plastic) and also replacing the thermostat.”

“2018 s4 45k miles. Shut engine, check coolant light came on, DTC P000000 with symptom code 33688. Noticed a leak onto the belly pan by the front right wheel. Otherwise the car ran normally, did not overheat or take long to warm up. In terms of cost, I got the water pump, thermostat, valve, and gasket for about $300 and getting charged ~$700 in labor for the job.”

I have a 2015 S4 with only 25,800 miles and my water pump is leaking coolant down the front of the engine. I first noticed smelling coolant while sitting in a drive-thru a few months ago. It’s a very slow leak, the coolant reservoir had dropped just below minimum, and I filled it up to Max maybe 500 miles ago after noticing that smell, and it’s about halfway down to Min again.

“I have a 2007 B7 Audi S4. For the past few months I’ve been having an issue where my right side aux radiator keeps breaking, whether it’s cracking and gushing coolant or slowly leaking. It happens every two or three weeks or so.” 

Although Audi and Volkswagen have already revised the thermostat housing a few times, it continues to be a common issue — especially in vehicles that are a few years old.

If you need to have the repair done out of warranty, a water pump and thermostat assembly costs around $400.

Getting it installed is a little more difficult in the B8 and B8.5 models is a little harder because the supercharger has to be removed to get to the water pump.

Getting it fixed at an Audi dealer can easily cost you over $1,000, but a VW or Audi specialist should be able to do the job for a much lower price.

The two side auxiliary radiators of the B6 and B7 S4 cost a little over $100 a piece and are not too difficult to replace. 

3. PCV Issues

The PCV valve or air oil separator of the B8 and B8.5 models of the Audi S4 are known to fail or develop cracks even before the car reaches the 100,000-mile mark 

The PCV (Positive Crankcase Ventilation) is an emissions control system that recirculates blowby gasses that are harmful to the environment back into the engine so that it burns up cleaner.

A broken PCV valve can affect the air-fuel mixture and also create excess pressure to build up in the crankcase, which causes the seals and gaskets to wear out quickly.

The PCV valve is also made out of plastic, which cracks over time and causes coolant to mix with oil.

Common symptoms of a faulty PCV valve include:

• Rough idle
• Misfiring
• Hissing or whistling noises
• Coolant mixing with oil
• Low coolant level
• Rear main seal leak
• Excessive oil consumption

Here’s how a few S4 owners on Audizine.com described their experience:

“I bought my first s4 b8. It’s a 2011 with Stronic gearbox. The car has an internal coolant leak, the coolant makes it to the oil. so the oil is a bit milky.

I bet it’s the PCV valve. Car runs fine, idles good, no misfires.”

“When I was having issues with my PCV, the car was squealing and I had crazy vacuum on the crankcase. I wasn’t having coolant loss or anything like that, like some others have.”

“The dealership quoted me $1,400 to replace the PCV as it is an 8 hour job with the removal of the supercharger.” 

A new PCV valve for the B8 S4 costs around $100 to $200, but the total repair will usually cost over $1,000 at the dealer because the supercharger has to be removed to access the old PCV valve.

A lot of B8 owners replace the PCV and water pump at the same time to save on future repair costs since both components are known to have issues and can be easily removed once the supercharger is out.

4. Timing Chain Problems

The 4.2-liter V8 engine of the B6 and B7 Audi S4 has a tendency to develop a timing chain rattle which can be quite expensive to fix.

The timing chain synchronizes the rotation of the engine’s internals, so when they stretch or break, it can cause major engine damage like bent valves or cracked pistons.

The most common issue with the timing chain is premature wear of the tensioners and guides which are made out of plastic. This causes the chains to become loose and rattle, and also causes it to wear out faster.

This is a common problem on the B6 and B7 models from 2004 to 2009 with the early model years up to 2006 being more prone to timing issues.

Common symptoms of a stretched timing chain include:

• Engine rattle
• Misfires
• Rough idle
• Hard starting
• Engine stall
• Reduced engine power
• Check engine light 
• Timing related trouble codes

It’s normal for the 4.2 V8 to rattle for 2 to 3 seconds on startup. If the rattle persists after the engine has been running for a while, the car likely has a timing chain issue or some other severe engine problem.

Here’s what a few S4 owners on Audizine.com had to say:

“I bought my 04 with 42k miles hoping those issues wouldn’t arrive for a long time, sure enough the service had to be done at 51k… I had a worn camshaft adjuster, which gave me misfire and timing over advanced codes. 1 guide had a crack in it, wasn’t in half yet though, and a few more had gouges in them.”

“I’ve seen failures happening to other members over the past 7 years from 35k-150k.”

“My 2004 is one of the cleanest you’ll find so it pains me to get rid of it. It’s in the shop now and they figure it needs about 5K in timing chain work. One of the guides went so it still runs and the chain still rotates.”

I’ve just replaced the timing chains on my 2005 B6 S4 Avant… The service was preemptive, I had just over 100k miles and while the car wasn’t giving me any problems I wanted it done before they let go. The decision to do the timing chain was a good one, with the engine out and the cover off the wear and tear on the timing chain systems was clearly evident with all the things you’d expect to find plus some of the guides were only being held in place by the chains. The cost of the timing chain service was about $6000 US for parts and labour.”

Replacing the timing chain is an engine out repair that can cost between $5,000 to $8,000 depending on who you take it to.

The timing chain kit alone costs around $1,400, and aside from experience and know-how, you’ll also need special tools to get it done properly.

When replacing the timing chain, many owners upgrade to the metal chain guide used in the RS4 which is more durable.

Related: Audi S4 Snow and Winter Driving (Solved & Explained)

5. Oil Consumption

Excessive oil consumption can affect different generations of the Audi S4 especially as they get older.

The 4.2 V8 of the B6 and B7 Audi S4 from 2004 to 2009 is more prone to excessive oil consumption, but quite a few B8 and B8.5 owners have also complained about similar problems.

Although Audi states the burning or losing 1 quart of oil every 600 miles is within spec, many owners are concerned that this is indicative of some underlying major engine problem that could cost several thousand dollars to fix.

Here’s how a few owners described their experience on Audizine.com:

“B6 S4 94K. My 2004 is one of the cleanest you’ll find so it pains me to get rid of it. It’s in the shop now and they figure it needs about 5K in timing chain work. One of the guides went so it still runs and the chain still rotates. They tell me it also has cylinder wall scoring, which would be causing my higher oil consumption… Over the last couple of years, I would be on a road trip and I’d have to add a quart. Then after another 20 minutes, the light would come on again.”

“I’ve recently bought an S4 B8.5, year of production is 2013. Unfortunately, I’m facing a real excessive oil consumption. The engine is burning like 3 liters every 1000 kilometers. I’ve recently replaced the PCV Valve and this didn’t help a lot. It didn’t actually help at all.”

“I recently bought a 2008 S4 Avant. There are 102K miles on the vehicle and it had a thorough maintenance history. I used Rosstech to pull any codes/readings and there is a slight misfire on cylinder 3&5. The car idles relatively smoothly with a very slight bump every 2-3 seconds. The gas mileage is ~330 miles/tank with mixed local and highway driving. However, there is very large oil consumption. 1.2 quarts in 340 miles of highway driving.”

There are a few possible culprits that can cause excessive oil consumption in an Audi S4. 

Some of the most common ones include:

• Faulty PCV valve
• Scored cylinder walls
• Worn valve stem seals
• Stuck piston rings
• Oil leaks

To fix problems like worn valve stem seals and piston rings, the engine has to be torn apart which can easily cost several thousand dollars in labor.

Oil leaks from the valve cover gasket, oil filter housing, timing cover or rear main seal can often be mistaken for oil consumption issues.

Replacing the rear main seal is also quite expensive to do because the transmission has to be disconnected from the engine. 

With the 4.2-liter V8, the valley pan gasket also has a tendency to leak oil. This can be costly to fix since the whole top of the engine has to be removed.

Many of the V8s also suffer from scored cylinder walls, which is an even bigger issue that will require a new engine block or an entire new engine.

In a lot of cases, owners just live with the issue and regularly check the oil level and top it up when necessary, especially if they don’t experience any drivability problems or don’t see any blue smoke from the exhaust, which means that oil is getting burned up in the combustion chamber. 

6. Rocker Arm Failure

Early model years of the B9 Audi S4 from 2018 to 2019 can suffer from rocker arm failures that can lead to severe engine damage.

This issue has only affected a small number of cars so far, but it can be very expensive to fix.

One common symptom of bad rocker arms is a loud ticking sound. It’s much louder than the normal ticking sounds from the injectors or the high pressure fuel pump.

If you continue to drive the car, the rocker arms can wear out and send metal shavings into the rest of the engine.

Here’s how a few S4 owners described their experience on AudiWorld.com:

“I bought my 2018 Audi S4 about a year ago and absolutely love it except when I started to hear rocker arms going bad with loud ticking when passing by walls, etc. I went ahead and asked the dealer for a quote on how much this would cost me to get this repaired. And honestly they didn’t get back to me except for one dealer who said it would need a new engine which I knew was ridiculous.”

“The ticking noise was VERY obvious as it was quite loud and annoying. I would get comments from other people about the noise all the time too. At first I had no idea what it could be, thought maybe the injectors or the HPFP. Last time it was at the dealer for service I mentioned it to them and they said it was normal. I learned through these forums about the issue with the rocker arms and had the car scheduled for service where I was going to make them replace the HPFP and then investigate the noise until they definitely diagnosed it, but the car died 3 days before that appointment.”

Other B9 S4 owners on Audizine.com had this to say:

“I have 2018 B9 S4 and currently over 90k miles. I had ticking noise on bank 1, last year it was gone somehow, had another ticking noise on bank2 and it seemed related with misfire on cyl5 when I ‘only exceed 6.5k to 7k rpm’. As soon as I dismount my engine out and open cylinder head, I found root cause of ticking noise. It was rocker arm failure as well as worn out camshaft due to rocker arm issue.”

“Yesterday, I picked up my car – after 63 days and $12,000 dollars. The cause was officially diagnosed as premature rocker arm failure.”

Getting the rocker arms replaced at the dealer can cost $10,000 or more since the cylinder head has to be torn apart and rebuilt.

All the parts required for the repair costs around $1,500. An independent Audi specialist might only charge around $5,000 or even less to replace the rocker arms.

If the rocker arm failure damages the engine and you’re out of warranty, it’s probably best to look for a used engine to swap in.

It’s also important to note that many Audi enthusiasts consider the rocker arm problem as overblown since only a very small percentage of cars out of the several thousand that Audi has sold has suffered from failures. 

7. Turbo Failure

The stock K03 turbos are a common point of failure for the B5 Audi S4, which was sold from 2000 to 2002.

Though many cars can last over 100,000 miles with the stock turbos, they will eventually fail at some point.

When the turbo starts failing, you’ll start to hear a high pitched whining sound that’s often described as similar to the sound a dentist’s drill makes when the turbo makes boost at wide open throttle.

It’s also usually the passenger side turbo that goes first.

Here’s what users on AudiWorld.com had to say:

“I went through 2 sets of turbos. First time around they made no sound, no smoke, no codes, no CEL, no boost. Second time around, horrible sounds, smoke to rival any james bond car ever, codes galore, CEL all over the place (the dash, the seats, the ashtray) 2psi – 3psi of boost at WOT.”

“Most expensive (pretty common repair) is a blown K03 turbo. I think mine was just shy of $5k to repair. But luckily there are plenty of aftermarket replacement turbos these days, and if you can DIY you’ll save at least 30 hours of audi labor charges.”

Although the turbos themselves aren’t that expensive, the engine has to be removed to be able to access the old blown turbos and install new ones.

The labor alone can easily cost $2,000 to $3,000 at an Audi shop.

Replacement turbos can cost around $500 to $600 a piece, but many owners also upgrade from the stock K03 turbos to K04 turbos which not only make more power but also last longer.

8. Crank Pulley Failure

The crankshaft pulley of the B8 and B8.5 Audi S4 has a tendency to break apart and separate, which damages the serpentine belt and other accessories in the front of the engine.

When the crank pulley fails and the serpentine belt breaks, the supercharger won’t provide any boost and the power steering will also stop working.

Here’s how S4 owners described their experience on Audizine.com:

“My crank pulley separated at 57k miles. Shredded my serpentine belt and my supercharger pulley. Ended up being $750, but the crank pulley(harmonic balancer) is covered under my extended warranty.”

“I thought I would chime in with my experience:62,xxx miles ; While driving home, I got a check coolant light so I pulled over and checked the coolant. Looked good so I kept going on my way. The light went off but then came back on miles later near my exit in conjunction with a myriad of other lights/warnings along with loss of power steering and finally a complete loss of power. Turns out, the Crankshaft Pulley separated from the rubber inner piece and shot about my engine bay taking out some other things in the process.”

“Mine failed at 86,000 miles. Totally out of the blue, during some hard acceleration. Left me stranded. Lost power steering and saw the temps creeping up so I pulled over to the side of the road. Looked like spaghetti in the engine bay from the shredded belt. Got it fixed at the dealer and they charged about $1,200.”

Another user on AudiWorld.com had this to say:

“I bought a ‘14 S4 back in September, I drove it for a little over 1k miles and the crank pulley (IE 207mm) snapped all the bolts holding it in place and trashed the pulley.” 

A new crankshaft pulley from Audi costs around $500 but aftermarket replacements are much cheaper at around $200.

Some owners replace the factory pulley which has a 2-piece design with aftermarket parts that are more durable.

Aside from replacing the pulley itself, you’ll also have to replace the serpentine belt and any other parts that were damaged.

Replacing the pulley and any other necessary parts will usually take an independent Audi specialist around 2 hours. 

9. Worn Suspension

The S4’s suspension has a tendency to wear out even at relatively lower mileages.

The worn ball joints and torn control arm bushings will eventually cause noticeable problems with the suspension.

Common symptoms of worn suspension components include:

• Creaking or clicking sounds
• Uneven tire wear
• Vibrations in steering wheel
• Handling issues
• Alignment problems

Here’s how a few owners on the r/AudiS4 subreddit described their experience:

“Just got quoted 1400$ for a replacement of 2 lower control arms on my b8.5 S4. I thought I had an alignment problem because of a super inside biased wear on my front tires, but the shop is saying that’s not the case.”

“I have a 2018 Audi S4 and my upper control arm passenger side needs some replacing.”

“I have a 2018 Audi S4 lowered on EMD spring 34k miles. I’ve been hearing a clicking sound on my passenger side wheel area, changed my upper control arm because the bushings are torn but clicking is still there. CV joint looks good, no tear, no grease, no play but I’m suspecting it’s the CV.”

New control arms from Audi are quite expensive and cost between $300 to $500 a piece. Getting them replaced at the dealer can easily cost over $1,000 because it will also require a few hours of labor.

Aftermarket replacements are cheaper with complete kits costing around $500 to $700.

You can also just replace the bushings which only cost a few dollars, but it will take some effort to remove the old ones and you’ll need a hydraulic press to install the new bushings. 

If you replace the entire control arm, you’ll also fix any issues with the ball joints.

10. Carbon Buildup

The B8 and later models of the Audi S4 use direct injection which can cause excess carbon buildup to form on the back of the intake valves.  

Since direct injection engines spray fuel directly into the combustion chamber, fuel doesn’t reach the back of the valves so carbon deposits don’t get regularly cleaned out.

The SAI (secondary air injection) system in the B8 cars can also have carbon buildup problems.

The 4.2-liter V8 FSI engine of the B7 RS4 is especially notorious for having carbon buildup issues. However, the regular B6 and B7 S4 with the 4.2 V8 don’t use direct injection.  

Common symptoms of excess carbon buildup include:

• Misfires
• Poor fuel economy
• Shaking or vibration at higher RPM
• Limp mode
• Check engine light

Audizine.com:

“My car is at the dealer now, carbon buildup got me. No CEL, but the codes were apparently present when they scanned it. They said it’s going to take a while to clean, despite not having to pull the head. 80~90% highway driving. 55k service. So I don’t scare anyone, this is the SAI cleaning AFAIK.”

“Well, like the other DI engines, the 3.0 also gets carbon buildup. I will be cleaning mine out soon. I took this picture when I had my SC off. Engine was at 60K. Not even close to how bad the V8 engine gets, but it’s still worse than what it should be.”

AudiRevolution.net

“I just did a quickie carbon clean on a 2012 S4 with 120K miles that had similar carbon buildup. I used the wire brush drill attachment and chemical method instead of walnut blasting because it came off after like two to three minutes per cylinder.”

The best way to clean out the carbon deposits is to have the intake valves professionally walnut blasted.

This can cost around $500 at an independent Audi or Euro specialist, and most enthusiasts recommend getting it done every 60,000 to 100,000 miles.

If you want to go the DIY route, you can also remove the intake manifold and carefully scrape off the carbon buildup manually after spraying it with solvent to soften it up a bit. 

Using premium gas can help reduce the carbon buildup, but it doesn’t completely eliminate the issue.

11. Coil Pack Issues

Another common maintenance item on a lot of Audi’s, including different generations of the S4, is the coil packs.

Audi and Volkswagen coil packs tend to have shorter lifespans, and can cause misfires when they fail.

It’s not uncommon to have to replace the coil packs every 60,000 miles. One or more coil packs can also go bad even before the car reaches 60,000 miles.

Signs of a faulty coil pack include:

• Rough idle
• Limp mode
• Misfiring
• Poor fuel economy
• Check engine light

Here’s how owners on Audizine.com described their issues:

“Just got a multiple misfire code on my 08 S4 Cabrio. Looks to be the coil pack on cylinder #5. I will swap it with the #6 and see if I get the misfire there just to verify. I will replace it regardless… It looks like one has been replaced but the others are probably original. My car has 65,000 miles on it.”

“I lost a coil pack yesterday in my 3.0T. I troubleshot with Carista, it called out cylinder 3 misfire, I had some 2.0T coil packs (black) so I popped it in and it worked like a champ so I went to the dealer and got a proper coil pack.”

If you’re getting a code for misfires in one cylinder, you can try switching around the coil packs to see if the misfire moves to another cylinder.

A new coil pack from Audi costs around $70 a piece. You can also get a set of 6 for around $400.

Aftermarket replacements from brands like Denso cost around $250 for a set of 6. 

When replacing the coil packs, it’s also a good idea to replace the spark plugs at the same time.

Related: 6 Most Common Problems of the Audi A4 (Explained)

Audi S4 Pros & Cons

Pros

• Quick acceleration
• Attractive yet unassuming appearance
• Good fuel economy
• Comfortable ride
• Refined interior
• Lots of advanced tech
• Luxurious daily driver
• Decent reliability
• All-wheel drive makes it feel planted

Cons

• Expensive parts and maintenance
• Limited interior storage
• Rivals have more character and performance

What Do The Reviews Say?

“From outward appearances, the Audi S4 doesn’t look much different from the A4. Keen observers will note the subtle badging and a few styling details; otherwise, it hides its potential for performance. That could be a good thing if you’re a driver who prefers to draw less attention to yourself but desires the kind of power and handling the S4 delivers.” 

“The S4 occupies the middle ground, delivering a delightful mix of refinement and athleticism.” 

“Our test car rocketed from 0 to 60 mph (with the help of launch control) in just 4.3 seconds. More impressive is the speed through the quarter mile: It blazed through at 107 mph. The engine makes plenty of power everywhere and it sounds great doing it. This is one of the quickest sedans in the class.”

“Handling is just as impressive. The S4 combines quick and accurate steering with standard all-wheel drive for excellent stability.” 

“The S4 is impressively comfortable. Driver fatigue, no matter the road, is minimal.”

2024 Audi S4 | Edmunds

What’s the Resale Value of an Audi S4?

Here’s a quick look at used car pricing for the Audi S4 on Edmunds at the time of writing.