What are the most common Audi S8 problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2001-2001 Audi S8 has 1 documented issues. The most frequently reported are: D2 4.2 V8 Timing Belt and Tensioner Service (Interference Engine). Of these, 1 is rated critical and should be addressed promptly.

Is the Audi S8 reliable?

The 2001-2001 Audi S8 has 1 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 1 issue is rated critical: D2 4.2 V8 Timing Belt and Tensioner Service (Interference Engine). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Audi S8 problems?

Repair costs for known Audi S8 issues range from $1,000 to $2,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, D2 4.2 V8 Timing Belt and Tensioner Service (Interference Engine), typically costs $1,000-$2,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

2001 Audi S8 Problems: 1 Issue Every Owner Should Know

2001 Audi S8 Problems: 1 Issue Every Owner Should Know | Au7o

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On the 2001-2003 Audi S8 4.2L 40V V8 (AYS), the first-generation D2 S8 uses the 4.2L 40-valve V8, an interference engine driven by a timing belt (intake cams) plus chains (exhaust cams). The belt is a maintenance-critical, age-and-mileage-limited item: Audi specifies replacement around 105k miles, but many specialists recommend shorter intervals (or every ~6 years) because failure is catastrophic — a snapped belt lets valves and pistons collide. Associated tensioners, rollers, and the water pump are commonly replaced together. On these older cars the chain tensioners on the exhaust side can also wear and rattle. This is the single most important service to verify on any D2 S8 purchase.

This issue also affects: Audi A4, Audi A1, Audi A5

Common Symptoms

Rattle on startup (worn chain tensioners)
Engine misfire or rough running
Difficulty starting
No-start / catastrophic failure if belt breaks

How to Fix

Replace the timing belt as a complete kit — belt, tensioner, idler/guide rollers, and water pump — at or before Audi's interval (and by age regardless of mileage). Use genuine/OE-quality components and set cam/crank timing precisely with the correct locking tools; this is a front-of-engine ('service position') job. Inspect the exhaust-side chain tensioners while in there. Always confirm timing-belt history (with receipts) before buying a D2 S8; if unknown, do it immediately.

What you need to fix it

The exact parts — OEM, plus what owners actually use. Skip the internet hunt.

Timing belt (4.2L 40v V8)
OEM078109119JOwners useContinental/ContiTech 078109119J, ContiTech CT1033 / TB297, Dayco 941064$35–$75
Genuine Audi PN confirmed on parts.audiusa.com and fits S8 D2 4.2 40v (engine AYS). The D2 S8 only ran 2001-2003 with the AYS 40v V8, which uses the 078-prefix belt 078109119J (supersedes 078109119C/G/H). NOTE: the EARLY D2 A8 1997-1999 (ABZ/AEW engine) uses a DIFFERENT belt, 077109119D — that is th
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Hydraulic timing belt tensioner / damper
OEM077109479DOwners useNTN 077109479D, INA 533 0036 30, VAG 077 109 479 D$50–$90
NTN-supplied hydraulic damper that works with the tensioner lever to set belt tension. Confirmed fitment across C5 A6/S6 4.2, D2 A8/S8, D3 A8 4.2, RS6 and Touareg V8 (ECS/Europa/FCP). Replace every belt service. Verified live across multiple OE vendors.
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Timing belt tensioner roller (lever-mounted)
OEM077109485EOwners useINA 531 0561 10, Ruville 55939, SKF VKM 11103$30–$70
Tensioner roller on the lever unit; vendors list 077109485E/F for the 4.2 40v kit (Cascade German / NGP / blauparts 'Deluxe' kits). Replaced with the belt. PN family confirmed across multiple kit listings; exact suffix (E vs F) varies by supersession.
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Timing belt idler roller (large)
OEM077109244EOwners useINA 532 0329 10, Ruville 55937, 077109244E$20–$50
Large idler/guide roller in the 4.2 40v timing system; listed in the OE deluxe kits for A6/S6/A8/S8 4.2 (Cascade German Parts, NGP). Bearing wear-item replaced with the belt.
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Timing belt relay/idler roller (small)
OEM077109244COwners useINA 532 0236 10, Ruville 55936, 077109244C$18–$45
Small relay/guide roller in the 4.2 40v timing layout; paired with the large idler in the OE kits (Cascade German / NGP). Replaced with the belt.
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Water pump (metal impeller) with gasket
OEM077121004POwners useGraf PA-857, Hepu P530, Geba$70–$130
Genuine Audi PN 077121004P confirmed on parts.audiusa.com for the 4.2 V8; updated metal-impeller design (early plastic-impeller pumps fail). Always replace during the belt job since it is belt-driven. Older kit listings cite 077121004M — that is a prior supersession of the same pump.
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Water pump gasket / seal
OEM078121043AOwners useGenuine VAG 078121043A, Elring, Victor Reinz$3–$12
Genuine Audi water-pump gasket confirmed on parts.audiusa.com / Pelican for 4.2 V8 (A6/A8/S6/S8/RS6/Touareg). Usually supplied with the OE pump but listed separately as a required sealing consumable for the job.
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Thermostat (4.2 V8, with O-ring)
OEM077121113DOwners useMahle/Behr TI 31 87 (082°C), Wahler, Genuine VAG 077121113D$15–$45
Commonly replaced while the front of the engine / cooling system is open during the belt+water-pump service. 077121113D (82C, Mahle, w/ O-ring) is the genuine 4.2 V8 thermostat per parts.audiusa.com and Europa Parts. Secondary/optional consumable, not strictly part of the belt itself — included beca
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Part links may earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$1,000 - $2,500

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Medium ConfidenceVerified0 reportsLast reported by owners Invalid DateReviewed Jun 2026

2001 Audi S8 Problems: 1 Issue Every Owner Should Know

All 1 Known Issues

2001-2003 Audi S8: D2 4.2 V8 Timing Belt and Tensioner Service (Interference Engine)#