Audi 4.0T V8 Reliability: The Definitive Guide (EA824 Hot-V Twin-Turbo)
Common Failure Points & Costs
| Component | Failure Mileage | Symptom | Est. Cost (USD) | Risk Level |
|---|---|---|---|---|
| Turbo Oil Screen (Oil Module) | 40k - 80k miles | Screeching noise, loss of power, check engine light, rough running | $700 - $1,700 (Preventive) / $5,000 - $10,000 (Turbo Replacement) | Critical |
| Turbochargers (Pair) | 50k - 90k miles | Oil starvation from clogged screen, bearing wear, shaft breakage | $5,000 - $10,000 | Critical |
| PCV / Oil Separator (Valley) | 60k - 100k miles | Whistling noise, strong vacuum at oil cap, idle instability, oil consumption | $1,000 - $2,000 | High |
| Carbon Buildup (Intake Valves) | 50k - 70k miles | Rough idle, hesitation, misfires, reduced power | $600 - $1,200 (Walnut Blasting) | Medium |
| High-Pressure Fuel Pump | 60k - 90k miles | Long crank, rough idle, fuel pressure codes | $600 - $1,000 | Medium |
| Ignition Coils | 40k - 60k miles | Misfire, check engine light, rough running | $400 - $800 (Set of 8) | Medium |
| Injectors (Direct Injection) | 80k - 120k miles | Misfire, fuel smell, hard start | $1,000 - $2,000 | Medium |
| Coolant Thermostat / Water Pump | 70k - 100k miles | Overheating, coolant leak | $800 - $1,500 | Medium |
Reliability Verdict
The Audi 4.0T V8 (EA824) is fundamentally strong but has one catastrophic design flaw: a tiny oil screen in the oil module that clogs and starves the turbos. Audi issued a recall (TSB 2044640) covering 26,000+ vehicles. If the recall has been completed or the screen serviced, the 4.0T is a solid engine. If not, budget for a $10,000 turbo replacement.
Audi 4.0T V8 Reliability: The $10,000 Oil Screen
The Audi 4.0T V8 (EA824) is a 420-560hp hot-V twin-turbo masterpiece that powers the RS6, RS7, S6, S7, and S8. It is one of the most advanced V8s ever built, with turbos nestled in the V of the engine for instant throttle response.
But there’s a problem: Audi placed a tiny mesh oil screen in the oil module to protect the turbos from debris. This screen clogs with sludge, starving the turbos of oil, causing catastrophic bearing failure and a $5,000 - $10,000 repair bill.
Audi issued a recall (TSB 2044640) covering over 26,000 vehicles. If the recall has been completed, the 4.0T is a fantastic engine. If not, you’re gambling with a five-figure repair.
This guide breaks down exactly what fails, when it fails, and how to buy a 4.0T without regret.
1. The EA824 Engine Family: Architecture & Applications
The 4.0T is part of Audi’s EA824 engine family, a hot-V twin-turbo V8 designed for performance and packaging efficiency.
Key Specifications
- Displacement: 4.0L (3,993cc)
- Configuration: 90° V8, DOHC, 4 valves per cylinder
- Turbo Layout: Hot-V (turbos in the V of the engine)
- Fuel Delivery: Direct Injection (FSI)
- Power Output:
- S6/S7/S8: 420hp
- RS6/RS7: 560hp (C7), 591hp (C7.5)
Applications
- C7 S6 (2013-2018): 420hp sedan
- C7 S7 (2013-2018): 420hp sportback
- D4 S8 (2013-2018): 520hp flagship sedan
- C7 RS6 Avant (2014-2018): 560hp wagon (not sold in US)
- C7 RS7 (2014-2018): 560hp sportback
The early C7 models (2013-2015) are the highest risk. The C7.5 facelift (2016-2018) has improved components but is not immune.
2. The Existential Risk: Turbo Oil Screen Failure
The turbo oil screen is a design-level flaw that can destroy the engine.
What is the Oil Screen?
Audi placed a small mesh screen (oil strainer) in the turbocharger oil-feed circuit within the oil module. The screen is designed to protect the turbos from debris.
How It Fails
- Screen Clogs: The screen clogs with sludge, varnish, or debris from extended oil intervals, poor oil quality, or cheap filters.
- Oil Starvation: The clogged screen starves the turbo bearings of oil.
- Bearing Wear: Rapid bearing wear, shaft play, turbine contact with the housing.
- Shaft Breakage: The turbo shaft breaks, sending metal debris through the engine.
Symptoms
- Screeching Noise: A high-pitched screech as the turbine contacts the housing.
- Loss of Power: Reduced boost, limp mode.
- Check Engine Light: Turbo underboost codes (P0299, P0234).
- Rough Running: Misfires, hard starting.
Failure Mileage
- 40,000 - 80,000 miles: Peak failure window.
- Some failures occur as early as 30,000 miles with poor maintenance.
Repair Cost
- Preventive Screen Service: $700 - $1,700 (labor-intensive, parts cheap).
- Turbo Replacement (Pair): $5,000 - $10,000 (both turbos, screen, oil, gaskets, labor).
[!WARNING] The Recall: Audi issued TSB 2044640 and a recall covering 2013-2017 S6, S7, S8, A8, and 2014-2017 RS7. If the recall has NOT been completed, the car is a ticking time bomb.
3. The Oil Screen Recall (TSB 2044640)
Audi’s recall is the single most important factor in 4.0T reliability.
Recall Scope
- Affected Models: 2013-2017 S6, S7, S8, A8; 2014-2017 RS7.
- Total Vehicles: Over 26,000 in the US.
- Reason: Blocked oil strainer can starve turbos, causing bearing wear, shaft breakage, and engine damage.
What the Recall Does
- Inspects the oil screen for clogging.
- Replaces the screen if clogged.
- Replaces turbos if damage has occurred.
- Extends turbo warranty.
Owner Experience
- Some owners received reimbursement for prior turbo repairs.
- Others report Audi refusing coverage if modifications are present or if the failure predated the recall.
- Many owners proactively delete the screen using aftermarket oil-line kits when upgrading to RS7 turbos.
[!TIP] Buying Advice: If you are purchasing a used 4.0T, verify that the recall has been completed. Ask for documentation. If the recall has not been done, negotiate $2,000 off the price or walk away.
4. PCV System Failures
The 4.0T uses a complex integrated PCV/oil-separator assembly in the valley. Failures are common.
Symptoms
- Whistling or Howling Noise: From the intake/valley area. The noise changes when you remove the oil cap.
- Strong Vacuum at Oil Cap: The cap is hard to remove due to excessive crankcase vacuum.
- Idle Instability: RPM flare or fluctuation when the oil cap is opened.
- Oil Consumption: Rising oil use as the separator degrades.
Diagnosis
- Oil Cap Test: Remove the oil cap while the engine is idling. If the idle changes dramatically or you hear a loud hissing, the PCV is failing.
Repair Cost
- PCV Replacement: $1,000 - $2,000 (parts + labor in the valley).
[!IMPORTANT] PCV Interaction: PCV failure exacerbates carbon buildup by increasing oil vapor in the intake streams. If you are doing carbon cleaning, consider replacing the PCV at the same time.
5. Carbon Buildup (Direct Injection)
The EA824 is a direct-injection V8, so intake-valve carbon buildup is an expected maintenance item.
Mechanism
- Fuel does not wash the intake valves.
- PCV and EGR vapors deposit oil/fuel mist on valves and ports.
- The mist bakes into carbon over time.
Symptoms
- Rough idle.
- Light-throttle stumbles.
- Misfires at low RPM.
- Reduced performance.
- Check engine light (misfire codes).
Maintenance Interval
- Every 50,000 - 70,000 miles: Walnut blasting or equivalent.
Repair Cost
- Carbon Cleaning: $600 - $1,200 at independent shops.
6. Maintenance Schedule: The “Survival Guide”
If you want your 4.0T to survive past 100,000 miles, you must follow an enthusiast maintenance schedule.
| Service | Audi Interval | Enthusiast Interval | Cost (Indie) |
|---|---|---|---|
| Engine Oil | 10,000 miles | 5,000 - 7,500 miles | $150 |
| Oil Screen Inspection | Never | 40,000 miles | $1,000 |
| Spark Plugs | 60,000 miles | 30,000 miles | $300 |
| Ignition Coils | As needed | 50,000 miles | $600 |
| Carbon Cleaning | Never | 50,000 miles | $800 |
| PCV Replacement | Never | 80,000 miles | $1,500 |
| Coolant Flush | 60,000 miles | 30,000 miles | $200 |
| Transmission Fluid | Lifetime | 60,000 miles | $400 |
[!IMPORTANT] Oil Change Interval is Critical: The single most effective way to prevent oil screen clogging is to change oil every 5,000 - 7,500 miles with high-quality synthetic.
7. Early vs Revised Engines (C7 vs C7.5)
There are important running changes within the EA824 family.
Early C7 (2013-2015)
- Risk Level: HIGH
- Why: Vulnerable oil screen design, higher turbo failure incidence.
- Recall Coverage: 2013-2017 models are covered by TSB 2044640.
- Verdict: Buyable, but only with recall completion verified.
Late C7 / C7.5 (2016-2018)
- Risk Level: MODERATE
- Why: Revised oiling system, updated PCV components.
- Recall Coverage: Some 2016-2017 models are covered; 2018+ have revised design.
- Verdict: The smart buy. Still has carbon buildup and PCV risk, but lower turbo failure rate.
8. Audi 4.0T vs BMW N63 vs Mercedes M278 vs Porsche 4.8L
How does the Audi 4.0T stack up against its German rivals?
| Feature | Audi 4.0T | BMW N63 | Mercedes M278 | Porsche 4.8L |
|---|---|---|---|---|
| Major Flaw | Turbo Oil Screen | Valve Stem Seals | Timing Chain Stretch | Bore Scoring (Alusil) |
| Repair Cost | $5k - $10k | $5k - $9k | $3k - $6k | $10k - $20k |
| Frequency | Moderate (40-80k mi) | High (60-90k mi) | Moderate (80-120k mi) | Moderate (70-100k mi) |
| Preventability | Yes (screen service) | No | Partially (check valves) | Partially (oil changes) |
| Longevity | Good (if recall done) | Poor (OG N63) | Good | Good (if no scoring) |
Verdict: The Mercedes M278 is the safest long-term bet. The Audi 4.0T (with recall completed) is in the middle—better than the early BMW N63, similar to the Porsche 4.8L if bore scoring is avoided. The BMW N63 is the riskiest.
9. 100,000-Mile Ownership Cost Projection
Here is a realistic budget for owning a 4.0T from 40,000 to 140,000 miles:
| Mileage | Expected Repairs | Cost |
|---|---|---|
| 40k - 50k | Oil screen service (preventive) | $1,200 |
| 50k - 60k | Carbon cleaning, ignition coils | $1,400 |
| 60k - 80k | PCV replacement, HPFP | $2,500 |
| 80k - 100k | Spark plugs, coolant thermostat | $800 |
| 100k - 120k | Transmission service, brakes | $2,000 |
| 120k - 140k | Injectors, misc leaks | $2,000 |
Total (40k - 140k miles): $9,900
Annual Average: $990/year (excluding routine oil changes and tires).
[!CAUTION] If the oil screen recall is NOT done and turbos fail, add $5,000 - $10,000 to the total.
10. Buying Advice: How to Buy a 4.0T Without Regret
If you want an RS7 or S6 and MUST have the 4.0T:
- Verify Oil Screen Recall Completion (TSB 2044640): This is non-negotiable. Ask for documentation.
- PCV Function Test: Start the car, let it idle, remove the oil cap. If you hear a loud whistling or the idle changes dramatically, the PCV is failing.
- Carbon Cleaning History: Ask if carbon cleaning has been done. If not, budget $1,000.
- Avoid 2013-2015 Models Without Recall: The early C7 cars are the highest risk.
- Buy a 2016+ C7.5 if Possible: The facelift models have improved components.
11. Conclusion
The Audi 4.0T V8 is a tragedy of engineering. It performs brilliantly, sounds incredible, and offers 560hp in the RS7. But the oil screen design is a catastrophic flaw that can turn a dream car into a financial nightmare.
Owning one is a calculated risk. If you buy a car with the recall completed, a clean PCV, and a commitment to 5,000-mile oil changes, it can be a rewarding experience. If you ignore the recall, it will bankrupt you.
Related Guides:
Expert Buying Advice
Only buy a 4.0T with documented oil screen recall completion (TSB 2044640) or proof of preventive screen service. Verify PCV function (no whistling noise). Avoid 2013-2015 models without recall. The 2016+ C7.5 RS7 and late S6/S7 are the sweet spot.