6 Serious Audi S6 C7 CEUC 4.0 V8 Twin Turbo Engine Problems

Doing your homework when it comes to buying a car is always a great idea. Every car has problems, especially performance models like the Audi S6 C7. A model can be fitted with various engines, some of them can be more, while some of them less problematic. So, you need to learn more about what engine is a good purchase. And we are going to help you out.

Are you interested in purchasing an Audi S6 and want to learn more about the Audi S6 C7 engine problems? You’re in the right place.

First, we are going to cover the basic specs of the 4.0 V8 engine. Then we will cover the common Audi S6 C7 Engine problems and also what are the applications of this engine. Lastly, we will answer some frequently asked questions. So, without further ado, let’s dive in.

Basic Audi S6 C7 CEUC 4.0 V8 Engine Specs

Now let’s first cover some of the specs of the 4.0 engine before we cover the common Audi S6 C7 engine problems.

This is a 90-degree V8 engine that was derived from the 4.2L engine that is produced by Audi and over the years, this new 4.0L replaced the good old 4.2L engine.

The engine block is made from hypereutectic Alusil aluminum alloy. This new alloy allows the engine to be very durable and corrosion-resistant. The thermal stress that Audi did on this block has proven that this new alloy greatly improved the engine’s heat-dissipating characteristics and longevity.

The engine uses very durable connecting rods and cast pistons, as well as a forged steel crankshaft.

Audi S6 C7 CEUC 4.0 V8 Twin Turbo engine image

This engine implements a double overhead camshaft design with four valves per cylinder and uses the Bosch MED 17 1.1 as an engine management system.

There are a few variations of this 4.0L engine but we are interested in the CEUC model. This was the engine that was included in the S6 and S7 C7 series produced by Audi.

This version is differentiated from the D4 series by using single induction for both turbochargers, and no power steering pump, and implements a different engine cover design.

The CEUC version comes in a single variation and this variation was rated at 309 kW (420hp) @ 5,000 rpm and 405 N-m (lb-ft) @ 1,400 rpm.

Common Audi S6 C7 Engine Problems

Let’s briefly list the most common problems with the 4.0L V8 twin-turbo engine.

Common Audi 4.0 V8 engine problems from the S6 C7 model include:

  • Ignition Coil And Spark Plug Failure
  • Turbo Failures
  • Motor Mounts Failures
  • Thermostat Failures
  • PCV Valve Failures
  • Carbon Buildup

Now that we know what are the main problems with the 4.0L engine, let’s now further elaborate on each of these issues and learn more about how serious these problems are and also how reliable this engine is overall.

Ignition Coil And Spark Plug Failure

The first problem on our list is the problem with spark plugs and ignition coils. These engines are high-performance engines and often can cause problems with spark plugs and coils.

This is the case because they draw a lot of electric current and this can cause excessive wear on these components. Also, the direct injection system affects their life in the process.

This is a common problem on a lot of Audi and Volkswagen engines. If you have an S6, you can expect to go through a set of spark plugs and coils every 30,000 miles or so.

Luckily, they are not that expensive. The expensive thing in this situation is the labor which is very high considering that it involves a lot of time. This is not your ordinary spark plug and coil replacement on your inline-4. These engines are tightly packed and getting around these components can be very tricky.

And replacing both coils and spark plugs is needed if you want to avoid some running issues down the line.

Symptoms associated with bad spark plugs and ignition coils include check engine light, engine misfires, rough idle, limp mode, and other running issues. So, make sure that you address the problem on time.

Turbo Failures

Turbo failures are probably the most notorious problem with these engines. Turbo failures will probably make you regret that you purchased this engine in the first place. This is why it is recommended to purchase the car with an extended warranty in order to be covered from a problem like this because it can get really expensive to fix.

The problem begins when the oil supply line filter ends up clogged. This will basically prevent the oil from going into the turbocharger and the turbocharger will fail.

The filter must be clean in order for the oil to go to the turbo. But these filters that Audi installed from the factory end up clogging rather quickly. So, the turbos will starve from oil and will eventually fail completely.

Audi reportedly issued a service bulletin for this problem but this unfortunately came a little too late for a lot of owners.

Symptoms associated with this problem will be the check engine light, reduced engine power, low oil pressure, and engine stall in some situations. The car will not be happy at all.

Luckily, what you can do is replace these filters and avoid ending up with this problem if they were not addressed previously.

Motor Mounts Failures

Motor mount failures are quite common on these engines as well. These engines are using something known as active motor mounts. The 4.0L unfortunately was the first application of this new technology.

These active motor mounts work differently and they are designed to isolate engine vibrations and smoothen the ride.

But as with every new technology, they are notorious for failing and causing all sorts of issues. The most common symptoms associated with this problem will be the excessive vibrations and banging coming from the engine bay. The engine will also move a lot while you press the throttle pedal.

There was another service bulletin for this problem. It is recommended that you update these motor mounts with the most recent revision if they are making a problem.

Also, there are aftermarket motor mounts for this engine that you can purchase. These aftermarket motor mounts are reportedly far more durable compared to the stock motor mounts.

Thermostat Failures

Thermostat failures are also common on these engines. The factory thermostat simply does not last for a very long time on these engines and a lot of these failures were reported by owners.

A thermostat in general is the component that allows coolant to circulate in the cooling system and this component can fail in an open or closed position.

If the thermostat fails in a closed position, your engine will overheat, while if the thermostat is open all the time, the engine will be difficult to get up to temperature and it could have a lot of issues until it warms up. So, monitor the temperatures carefully and replace the component if needed.

PCV Valve/Oil Separator Failures

PCV valve failures on these engines are also a very common occurrence in Audi engines. They just tend to fail on these engines very frequently.

These PCV valves have the task to purge the gasses that were collected into the crankcase. When they are not purging the gasses, you will end up with a situation where you have poor engine idle, and the engine misfires.

A new part for your Audi is about $287. More expensive will probably be labor for this job because this PCV valve is located in a rather tight area.

Carbon Buildup

Carbon buildup is also an issue with this engine. Even though a lot of owners would say it’s not, it actually is a problem because of the direct injection system that this engine is using.

Especially on higher mileage engines it can happen. This is why it is always recommended that you do a walnut blast every 60,000 miles in order to make sure that everything is nice and clean on the intake valves.

The process can be expensive because the engine has to come off, but that’s how things are with these Audi engines. Nothing comes cheap.

Which Models Include The C7 CEUC 4.0 V8 Twin Turbo Engine?

Now let’s take a look at which models this engine was included in.

  • 2012 – 2018 Audi C7 S6
  • 2012 – 2018 Audi C7 S7


In this article, we have covered quite a bit when it comes to the 4.0L V8 engine by Audi. First, we covered the basic specs of this engine and learned more about the numbers.

Then, we discussed the Audi S6 C7 engine problems, we learned what troubles this engine the most and also what are the symptoms when these problems occur. Overall, the 4.0L engine is not bad but can be very expensive to maintain.


What Are The Common Problems With the Audi S6 C7 4.0 TFSI Engine?

Common problems on this engine include spark plug and ignition coil failures, PCV valve failures, carbon buildup, turbocharger failures, motor mount failures, and also thermostat failures.

Is The Audi S6 C7 4.0 V8 Turbo TFSI Engine Reliable?

Besides the turbocharger failure caused by dirty oil screens, there are no major reliability issues. Make sure that you update these screens if you want to avoid complete failure on the turbochargers and avoid paying hefty fees to replace them.

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