Audi S5 B9 Ultimate Guide

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We won’t lie, before this guide, the B9 S5 wasn’t really on our radar for good-looking Audi’s. But man, if modded right, these things can be beautiful machines. The Audi S5 B9 was first introduced in 2017 and is still in production today. It is the second generation of the S5. It was built on the Volkswagen Group’s MLB platform. The B9 went through a significant, much-needed, redesign that made us really like the new and improved S5. The front and rear, headlights, LED lighting, grille, and body all had significant aesthetic improvements to make it more modern and aggressive. There are three different body styles offered: coupe, sportback, and cabriolet (convertible).

Also newly featured in the B9 S5 is an updated 3.0 TFSI with a turbocharger, instead of the previous supercharged version. This CWGD V6 twin-scroll turbocharged engine puts down 349hp (260 kW) and 369 lb-ft (500Nm) of torque. There were many advantages to switching to this engine: lighter, more powerful, cheaper to maintain, and reduced turbo lag. As opposed to the supercharged 3.0 TFSI, this engine is much more mod friendly and can get some serious gains without spending as much money.

Audi S5 B9 Specs

In this section, we will be going over some interior and exterior specs for the two-door convertible, two-door coupe, and four-door sportback.

Audi S5 B9 Pricing

In this portion, we’ll be covering new and used prices for the S5 B9. For new prices, a 2022 S5 Premium cabriolet starts at $63,400, a Premium Plus S5 cabriolet starts at $67,000, and a Prestige S5 cabriolet starts at $71,500. A 2022 S5 Premium coupe starts at $55,300, a Premium Plus S5 coupe starts at $58,900, and a Prestige S5 coupe starts at $63,400. And lastly, a 2022 Premium S5 sportback starts at $55,300, a Premium Plus S5 sportback starts at $58,900, and a Prestige S5 sportback starts at $63,700. On the used side, depending on what year and mileage, an Audi S5 can range anywhere from $29,495 – $75,991. If you are confused about Audi trims, here is a little write-up on the different Audi trims.

Now, let’s jump into some common problems these vehicles have seen over the last 5 years.

The 6 Most Common Audi S5 B9 Engine Problems

1. Ignition coil or coil pack failure
2. Start/stop system failure
3. Premature thermostat failure
4. Pre Sense issues
5. Passenger airbag detection issues
6. Interior/exterior rattling noises

1. Ignition Coil or Coil Pack Failure

Premature ignition coil failure is very common in many modern engines nowadays, especially VW and Audi engines. Ignition coils supply voltage carried from the battery to the spark plug. This allows the spark plug to create a spark in the combustion chamber initiating engine combustion. There is one ignition coil per cylinder, so the S5 B9 has 6 cylinders, which means it has 6 ignition coils and spark plugs. One failing ignition coil will cause a cylinder misfire, while multiple failing ignition coils may cause the engine not to start.

There are a few reasons ignition coils can fail: normal wear and tear, defective coils, or engines that have been modified for more power. If you plan on modding your engine for more power, we not only advise getting new ignition coils, but also 1-step colder spark plugs. We advise replacing the spark plugs and ignition coils together every 40,000 miles.

Symptoms of Ignition Coil or Coil Pack Failure:

• Check Engine Light (CEL) or Malfunction Indicator Light (MIL) illuminating
• Cylinder misfires with P0300 – P0306 fault codes present
• Rough idle
• Poor engine performance
• Decreased fuel economy
• Engine may not start or take a while

Ignition Coil Replacement Options:

When ignition coils or spark plugs go bad, there are a couple of options: replace them with OEM units or replace them with high-performance units. Replacing ignition coils and spark plugs is not the hardest DIY if you know where they are located and the proper spark plug gap. If you aren’t wanting to DIY the replacement, a local mechanic would likely charge around $500 to replace both the coils and spark plugs.

Audi S5 B9 OEM Ignition Coils
Audi S5 B9 OEM Spark Plugs

DIY Difficulty: Easy

2. Start/Stop System Failure

The Audi start/stop system has had many lawsuits in the past and TSB’s, but Audi explains the complaints are how the system is supposed to operate. The start-stop system should automatically shut off the engine at a stop to eliminate emissions while preserving fuel. In theory, this should be great technology, but it comes with some problems and not all consumers love it. Put simply in Audi’s terms, deactivate the system if it makes you don’t like it. However, I don’t think they realize how tedious it is for customers to have to turn it off every time they step into the vehicle.

Start/Stop System Problems:

• Slow reactivation
• Delayed acceleration response
• Engine starting 10 times or more a day
• Many requirements need to be met for it to function
• Premature power steering/brakes shut off
• Rollaway threat

There are many requirements for the engine to be switched off, here is a link for a more in-depth guide on how Audi’s Start-Stop System works. The reason this is classified as a common problem is that there are so many complaints about it actually working properly, but it may seem that not all customers may be informed on how the system is supposed to work. Common complaints are that the Start-Stop system doesn’t shut down when the customer thinks it should, the engine is not switched on or off automatically, or the engine restarts for unknown reasons.

3. Premature Thermostat Failure

Another pretty common failure in many modern engines is thermostat failure. A thermostat regulates how much coolant is cooled by the radiator before being recycled and the amount of coolant that is sent back into the engine. The factory thermostat in early S5 B9’s has been known to only last up to 20,000 – 30,000 miles. This is definitely not normal, but it seems that Audi has made revisions on later S5 B9’s. Typically, a thermostat should last anywhere from 80,000 – 100,000 miles.

Symptoms of Premature Thermostat Failure:

• Engine overheating
• Unusually high engine temps
• Engine running poorly
• Engine coolant leaks
• White steam emitting from the engine

Thermostat Replacement Options:

When a thermostat goes out, there is only one thing to do and it is to replace it. We would advise replacing the thermostat with a newer version of the OEM unit. Again, Audi has improved the thermostat, so it should last much longer than 25,000 miles. Unfortunately, the front bumper needs to be removed to replace the thermostat, so it isn’t the easiest DIY. A local mechanic or dealer would likely charge around $1,000 mainly due to labor costs.

DIY Difficulty: Easy

4. Audi Pre Sense® Issues

This is a common problem on many Audis that seems to get alleviated after the first few model years of a generation. Audi Pre sense® is Audi’s tech and safety package. It uses cameras and sensors to track the vehicle’s surroundings, such as pedestrians or other vehicles. Features such as the brakes automatically if the vehicle suspects a collision or tightening the seatbelt tension for safety. Other features included in Pre Sense Basic are:

• Turn assist
• Adaptive cruise control with Stop&Go function
• Adaptive cruise assist
• Collision avoidance assist
• Active lane assist
• Parking system plus
• And many more.

Symptoms of Audi Pre Sense® Issues:

• Pre sense® engaging for no reason
• Sudden braking
• Random beeping noises
• Pedestrian/cyclist detected
• Collision expected
• “Audi Pre sense malfunction! Please contact service” error message on dash

S5 B9 customers have been complaining about the sensors being bugged and pre sense activating for no reason. Not only is this dangerous to the driver, but also to other drivers on the road. The main issue is pre sense detecting a potential collision and slamming on the brakes unnecessarily. It has been said that many Audi dealerships claim “it isn’t a perfect system”. With that said, there are different sensitivity settings: Low, Medium, and Late. Some customers have found this to help a little bit. Other customers have simply turned Pre Sense off. We do not advise doing this but do advise going to your local Audi dealership to see what they say.

5. Passenger Airbag Detection Issues

Not a huge issue, but more of an annoyance, the passenger airbag light refusing to go off when there isn’t a passenger sitting in the front seat. It was alarming enough that Audi issued a recall on over 144,000 2017-2018 S4/S5s. The underlying issue was the detection system and the associated cable was too sensitive. Audi technicians were told to apply a software patch that adjusts the system’s threshold. Therefore, if you happen to be in the market for a used S5 B9, make sure any 2017 or 2018 S5s have had this issue addressed.

A passenger airbag detection system is in place to prevent unnecessary airbag deployment. A nonfunctioning passenger airbag detection system can be catastrophic if a crash were to occur.

6. Interior/Exterior Rattles

Lastly, another annoying common problem that has been reported by many S5 B9 owners is rattles inside and outside of the vehicle. Some owners have even reported this as soon as they drove it off the lot brand new. Places that can be susceptible to rattling:

• Rear speaker
• Door panels
• Sunroof shade area
• Trunk
• Accent light strip on the doors
• Seat belts
• Dashboard

Again, this isn’t a major problem, but it can be annoying if it is your daily driver.

Audi S5 B9 Mods

Now that we’ve covered the common problems, let’s jump into the fun part. We’ve seen many B9 S5 owners pushing sub 12 quarter-miles, so this gets us excited. Unlike the supercharged 3.0 TFSI used in the previous S5 generation, the current 3.0 TFSI is able to take on a lot more power without spending a lot of money. The 5 mods listed below are a great starting point for someone looking to push 415+ hp.

1. ECU Tune
2. Down Pipe
3. Intercooler
4. Charge pipe kit with upgraded BOV
5. Air Intake

If you are wanting to read more on these 5 best mods, here is a mod guide we wrote for the Audi S5 B9.

Audi S5 B9 Reliability

When it comes to the reliability of the Audi S5 B9, there isn’t much information to go on, besides customers over the last 5 years. So, based on this, the engine is very reliable but expensive to maintain. However, there are many mechanical and electrical bugs that B9 S5 owners have experienced. The big two are interior and exterior rattles and Audi pre sense® issues. Audi dealers have been putting bandaids on the rattles, while a software update has somewhat alleviated the pre sense® issues. One thing to note is that these vehicles are only 5 years old, so Audi is still going to be improving everything about them. Therefore, if you are in the market for an Audi B5 S9, we would advise getting the newest model as it has given Audi 5-6 years to refine the vehicle.

When it comes to the S5, the S4 is a common comparison. Therefore, we’ve broke it down for you in our S5 vs S4 article.