2008-2012 Audi S5 Exhaust Manifold: Cracks, Leaks, and V8 vs. 3.0T V6 Guide
This definitive guide covers the critical differences between the V8 and V6 manifolds, common failure symptoms like ticking noises, and a crucial emissions recall you need to know about.
- The single most important factor is your engine: 2008-2012 S5 Coupés use a 4.2L V8, while 2010-2012 S5 Cabriolets use a 3.0T V6. The manifolds are not interchangeable.
- A ticking noise when the engine is cold is the most common symptom of a cracked manifold or leaking gasket.
- Check for Emissions Recall 26J2 on 2008-2010 4.2L V8 models; this recall replaces the manifolds/catalysts with improved parts.
- Replacement is a very difficult job due to tight access and the high likelihood of seized or broken bolts, making professional installation highly recommended.
V8 vs. V6: A Critical Distinction for the 2008-2012 S5
Before diagnosing or buying an exhaust manifold for a 2008-2012 Audi S5, you must identify your engine. The correct part depends entirely on the engine and body style, as two different engines were used during this period.
- 2008-2012 S5 Coupé: Equipped with a 4.2L V8 (Engine Code: CAUA).
- 2010-2012 S5 Cabriolet (Convertible): Equipped with a 3.0L Supercharged V6 (TFSI) (Engine Code: CAKA).
These two engines use completely different exhaust manifolds that are not interchangeable. Always verify your vehicle's body style and engine before ordering a part.
Warning: Part numbers starting with 079... are for the 4.2L V8 engine. Part numbers starting with 06E... are for the 3.0L Supercharged V6 engine. Double-check the part number for your specific application.
Symptoms of a Failing S5 Exhaust Manifold
A cracked manifold or a failed gasket will leak exhaust before it can be treated by the catalytic converter. This can cause several noticeable symptoms.
- Ticking or Puffing Noise from Engine Bay: This is the most common sign. The noise is often loudest when the engine is cold and may quiet down or disappear as the engine warms up and the metal expands, temporarily sealing the crack.
- Exhaust Fumes in the Cabin: A strong smell of exhaust inside the car, especially when stopped or moving slowly, is a serious symptom. Leaking gases can be drawn into the fresh air intake for the climate control system, posing a health risk.
- Check Engine Light: A leak can allow extra oxygen into the exhaust stream. This can confuse the oxygen sensors, leading to fault codes for a lean fuel mixture or, more commonly, catalyst inefficiency codes like P0420 and P0430.
- Decreased Performance and Fuel Economy: An exhaust leak disrupts the carefully managed pressure of the exhaust system and can throw off sensor readings, leading to a noticeable loss of power and worse gas mileage.
- Visible Soot or Black Marks: You may see black, sooty trails around the crack on the manifold or on nearby engine components where the hot exhaust gas is escaping.
Known Issues, TSBs, and Recalls
Emissions Recall 26J2 (4.2L V8 Only)
For certain 2008-2010 Audi S5 Coupé models with the 4.2L V8 engine, Audi issued an emissions recall (Code: 26J2). The recall addresses the potential for the factory-installed catalytic converters to degrade over time and fail to meet emissions standards. Since the converters are integrated into the manifolds, the corrective action is to replace both exhaust manifold/catalyst assemblies with improved parts, free of charge.
When buying a used 4.2L S5 or a used manifold, it is highly beneficial to check with an Audi dealer to see if this recall work has been performed on the vehicle. A car with the updated parts is more desirable.
Buying a Used S5 Exhaust Manifold: What to Check
A used OEM manifold can be a great value, especially given the high cost of new units. However, careful inspection is crucial.
- Confirm Engine Compatibility: This is the most important step. Get the part number and verify it matches your engine (4.2L V8 or 3.0T V6) and the correct side of the vehicle (left/driver or right/passenger).
- Inspect for Cracks: Meticulously check the entire manifold, especially around the welds, the flange that bolts to the cylinder head, and where the individual runners merge. Hairline cracks can be hard to see but will cause leaks.
- Check for Warping: Place a straight edge across the cylinder head mounting flange. If there are any significant gaps, the manifold is warped and will not seal properly, even with a new gasket.
- Examine the Catalytic Converter: Look inside the converter outlet. The ceramic honeycomb structure should be intact. Avoid any unit with broken, melted, or rattling pieces inside. A damaged catalyst will fail an emissions test and can cause blockages.
- Check Studs and Threads: Ensure any integrated studs are intact and that the threads for the oxygen sensors are not stripped or damaged. Repairing these threads can be difficult.
Pro Tip: For the 4.2L V8, manifolds are known to crack. A used part is still a viable option, but the inspection for cracks is paramount. For the 3.0T V6, catalyst failure is more common than the manifold itself cracking.
Replacement Overview & Difficulty
Replacing the exhaust manifold on an Audi S5 is a difficult and time-consuming job, best suited for experienced technicians or very skilled DIY mechanics.
- Difficulty Rating: 5/5 (V8), 4/5 (V6)
- Primary Challenges: Access to the manifold bolts is extremely limited, especially on the V8 engine. It often requires removing other components to create clearance. The bolts and studs are exposed to extreme heat cycles and are frequently rusted, seized, or broken during removal. Extracting broken studs from the aluminum cylinder head is a delicate process that can significantly increase labor time.
- Required Parts: Always use new exhaust manifold gaskets and one-time-use stretch bolts or nuts when installing the replacement part. It is also wise to replace oxygen sensors at the same time, as they are often difficult to remove from the old manifold without damage.
| Part Type | Estimated Cost | Notes |
|---|---|---|
| New OEM | $1,800 - $3,300 (per side) | Includes integrated catalytic converter. Price varies by engine. |
| New Aftermarket | $450 - $1,500 (per side) | Quality and catalyst efficiency can vary widely. May not be legal in all states (e.g., California). |
| Used OEM | $150 - $600 (per side) | A cost-effective option, but requires careful inspection for cracks and catalyst damage. |
| Shop Labor | $900 - $1,500+ | Labor can increase significantly if bolts break during removal. |
| Engine | Side | Part Numbers |
|---|---|---|
| 4.2L V8 (Coupé) | Left (Driver) | 079253033AK, 079253033AD |
| Right (Passenger) | 079253034AK, 079253034H | |
| 3.0T V6 (Cabriolet) | Left (Driver) | 06E253031AB, 06E253031AC, 06E253031N, 06E253033H, 06E253033T |
| Right (Passenger) | 06E253032AB, 06E253032AC, 06E253032M, 06E253032N, 06E253032P, 06E253034AA |
Frequently Asked Questions (FAQ)
Can I drive with a leaking exhaust manifold?
It is not recommended. While the car may be drivable, leaking hot exhaust gases can damage nearby plastic and rubber components under the hood, creating a fire hazard. Furthermore, fumes entering the cabin are a serious health risk due to carbon monoxide.
Will a cracked manifold cause my car to fail an emissions test?
Yes, almost certainly. The leak allows un-metered oxygen into the exhaust, which will cause the oxygen sensors to report incorrect data to the engine computer. More importantly, it allows untreated exhaust gases to escape before they pass through the integrated catalytic converter, resulting in an automatic failure.
Why is the OEM part so expensive?
The original equipment manifold includes a high-quality, complex catalytic converter integrated into its design. Catalytic converters contain precious metals like platinum, palladium, and rhodium, which are very expensive. The cost reflects both the complex manufacturing and the value of these materials.
Should I replace both manifolds at the same time?
It is often recommended. The manifolds on both sides of the engine have been subjected to the same mileage and heat cycles. If one has failed due to cracking or catalyst degradation, the other may not be far behind. Given the high labor cost for this job, replacing both at once can save you money in the long run by avoiding a second tear-down.
Technical Specifications
OEM Part Numbers: 079253033AK 079253033AD 079253034AK 079253034H 06E253031AB 06E253031AC 06E253031N 06E253033H 06E253033T 06E253032AB 06E253032AC 06E253032M 06E253032N 06E253032P 06E253034AA
Integrated primary catalytic converter. Material is typically cast iron or a high-temperature steel alloy.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Audi S5: