Every Audi Enthusiast Should Buying a Used S5 Engine

The Audi S5 has always occupied an interesting position in the Audi lineup not quite as extreme as the RS5, not as understated as the A5, but precisely calibrated to deliver the kind of confident, composed performance that suits buyers who want to move quickly without announcing it. Across its production history, the S5 has used several distinct engine families, each with its own character and its own set of ownership considerations. If you're currently in the market for an  Audi s5 engine for sale, the single most important thing you can do before any other step is confirm which generation and which engine you're actually dealing with because the answer shapes every subsequent decision in your search.

Two Very Different Engines Across Two Very Different Generations

The B8 generation S5 (2007 through 2016) used the 4.2-liter naturally aspirated V8 designated the CAUA in early production and later the CGTA, producing 354 horsepower from a high-revving, naturally aspirated design that revved freely to 7,000 RPM and delivered the kind of linear, sonically rich power delivery that S5 enthusiasts still miss in later models. This is one of the last naturally aspirated V8s Audi fitted to a production performance car in the compact executive segment, and its sound and character have made it a genuinely collectible engine as naturally aspirated performance becomes increasingly scarce.

The B9 generation S5 (2017 onwards) uses the 3.0-liter TFSI turbocharged V6, specifically the DEYB engine code producing 349 horsepower and 369 lb-ft of torque. This engine is faster in straight-line acceleration and more fuel-efficient than the V8 it replaced, but it delivers its performance in the modern turbocharged manner strong and broad rather than linear and sonically compelling. The turbocharged V6 is the more technologically current of the two, with direct injection, variable valve timing, and an integrated cooling system that maintains consistent operating temperatures across a wide range of driving conditions.

Both engines are excellent, but they are completely different in character, completely different in their failure modes, and completely different in their inspection priorities. Knowing which generation you own and which engine you need is not a minor detail it is the foundation of a successful sourcing process.

The 4.2 V8 in the B8 S5: What Makes It Special and Where It's Vulnerable

The 4.2-liter naturally aspirated V8 in the B8 S5 is one of the more straightforward Audi engines to evaluate as a used purchase, relative to the turbocharged alternatives, because its failure modes are largely predictable and its condition is largely legible through inspection. The most common cause of 4.2 V8 failure in S5 applications is oil sump pickup tube failure — a known defect in early production B8 engines where the oil sump baffle and pickup tube design allowed oil starvation during high-g cornering or hard braking on track. Audi issued a technical service bulletin addressing this with a revised sump design, and any used 4.2 V8 you evaluate should be checked for whether this update was applied.

Secondary failure modes include carbon buildup on the intake valves (universal for direct-injected engines of this era), valve stem seal wear on higher-mileage units that causes oil consumption and blue smoke on cold startup, and timing chain stretch on engines with extended service intervals. The 4.2's chain system is less complex than some Audi engines but is still sensitive to oil quality confirm service history with 5W-40 full synthetic at the correct specification before any purchase.

Compression testing across all eight cylinders should show consistent readings between 155 and 185 PSI. Any cylinder reading significantly below the others requires a leak-down test to identify the cause. Inspect the spark plugs if accessible oil-fouled plugs from specific cylinders pinpoint valve stem seal wear that the compression test alone may not fully reveal.

The 3.0 TFSI in the B9 S5: The Modern Performance Standard

The B9 S5's 3.0-liter TFSI V6 is a more complex engine that requires a more nuanced inspection approach. The same carbon buildup concern that applies to the 4.2 V8 applies here — in fact, it is more significant given that the 3.0 TFSI was introduced before Audi's port-plus-direct injection system became available on this engine family. Budget for walnut blasting at installation if the engine's carbon history is unknown.

The supercharger bypass valve is a documented wear item on all 3.0 TFSI applications including the S5 a failing bypass valve causes a characteristic hissing under moderate acceleration and a flat response in the 2,000 to 3,500 RPM range. Ask whether this component has been replaced, and factor the cost of replacement into your offer if not. The timing chain on the B9 generation 3.0 TFSI is generally durable with correct service, but cold-start rattle on any used example should trigger a careful conversation about chain and tensioner condition before proceeding.

Pricing for used B8 S5 4.2 V8 engines in good condition currently ranges from $2,500 to $6,000 depending on mileage and documentation. B9 generation 3.0 TFSI engines from S5 applications typically range from $3,500 to $7,500, reflecting their more recent production vintage and more complex ancillary components. In both cases, the premium for a documented low-mileage unit from a seller who can provide the donor vehicle's VIN and service history is consistently justified by the lower risk and better warranty prospects it represents.

🔧 Turbo Auto Parts — Audi S5 Engines for Every Generation, Backed by 3 Years of Coverage

Your Audi S5 deserves a replacement engine sourced with the same care and precision Audi put into building it. Turbo Auto Parts carries quality used and remanufactured engines across both S5 generations — the naturally aspirated V8 and the turbocharged V6 — and we back every sale with our 3-Year Parts Warranty. We offer free shipping throughout the continental United States, with fitment specialists who verify engine codes by VIN before your order ships. Get the right engine, backed by the right warranty.

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