The B7 S4 is the last Audi S4 with a naturally aspirated V8, and many enthusiasts consider it the most rewarding S4 to drive. The 4.2-litre BBK engine produces 344 hp and revs freely to 7,200 rpm, paired exclusively with quattro AWD and a choice of 6-speed manual or ZF 6HP19 Tiptronic automatic. It uses multi-point port injection (not FSI like the RS4), which avoids carbon buildup issues. This report covers the saloon and Avant; the B7 S4 Cabriolet stayed on sale into 2009. The car's reputation is dominated by the timing chain and tensioner service, which is expensive but well-documented.· more· less
Plastic chain guides and tensioners wear out, causing startup rattle and risk of chain skip · more· less
This is the most critical and expensive issue on the B7 S4. The 4.2L V8 uses timing chains located at the rear of the engine against the firewall, meaning the engine or subframe must be lowered for access. The plastic chain guides deteriorate in the high-heat, high-vibration environment, and the hydraulic tensioners lose pressure over time. Symptoms start with a brief rattle on cold startup (the so-called death rattle) that progressively worsens. If the guides disintegrate or the chain skips, catastrophic valve damage can result. Failures have been reported from as early as 60,000 km, though most occur between 100,000 and 160,000 km. Parts for a complete timing chain service kit cost approximately €800-1,400 for OEM components. Labor is typically 16-25 hours because of rear-engine access requirements, pushing total cost to €3,500-6,000 at a specialist. Audi dealers can charge more. Frequent oil changes with quality oil help slow guide wear, but preventive replacement is the only reliable solution. When buying, always ask whether this service has been completed.
Excessive oil consumption
up to €4,0002 of 8
Valve stem seals harden and crack, causing the engine to burn excessive oil · more· less
The 4.2L V8 in the B7 S4 is prone to elevated oil consumption, and the 2008 owner's manual gives up to 0.5 litre per 1,000 km as the allowance. The primary cause is hardened and cracked valve stem seals, which allow oil to leak past the valve guides and into the combustion chambers. The engine bay is tightly packed, causing the V8 to run hotter than in larger Audi models, which accelerates seal degradation. Mild cases (1 litre per 2,000-3,000 km) can be managed by topping up oil regularly. Severe cases require valve seal replacement, which involves significant engine disassembly and costs €3,000-4,000 at a specialist. A PCV valve failure can also contribute to oil consumption; replacing the PCV system costs approximately €300-500 and should be checked first as a less expensive cause. Blue smoke on startup or under hard acceleration indicates oil burning.
Front suspension control arm wear
up to €1,8003 of 8
Multi-link front suspension has 8 control arms with bushings that wear out, causing clunking and vague steering · more· less
The B7 S4 shares the multi-link front suspension with the B7 A4, featuring 4 control arms per side (8 total). The rubber bushings and ball joints are known to wear relatively quickly, typically between 80,000 and 120,000 km. Worn bushings cause clunking over bumps, vague steering feel, uneven tire wear, and can lead to MOT/TUV failure. Audi issued a TSB for the upper control arm bushings, which can crack or have the metal spacer unbond from the rubber. A complete front control arm kit with all 8 arms, bushings, and hardware costs €300-600 for aftermarket parts or €600-1,000 for OEM. Labor to replace all 8 arms typically runs €400-800 at an independent specialist. Most B7 S4s at this age will need at least one set of control arms during ownership.
Ignition coil pack failure
up to €5004 of 8
Coil packs degrade from engine heat, causing misfires on individual cylinders · more· less
The 4.2 V8 has 8 ignition coil packs, one per cylinder, and they are prone to failure from heat exposure. Symptoms include engine misfires, rough idle, and individual cylinder misfire codes (P0300-P0308). Coil failures typically begin around 60,000-80,000 km, and once one fails, others often follow within the next 20,000 km. Individual OEM coils cost approximately €20-35 each. It is common practice to replace all 8 simultaneously along with spark plugs, bringing the total to €200-500 including labor. This is a straightforward and inexpensive repair relative to other V8 issues, but ignoring misfires can damage the catalytic converters.
Coolant system plastic connector failures
up to €8005 of 8
Plastic T-pieces, elbows, and connectors in the cooling system become brittle and crack · more· less
The cooling system on the 4.2 V8 uses several plastic connectors, T-pieces, and elbows that become brittle with age and heat cycling. The upper radiator hose elbow on the passenger side is particularly prone to snapping. When a connector fails, coolant leaks out and the engine can overheat quickly. Individual connectors are inexpensive (€10-30 each), but the labor can be significant depending on location, and it is advisable to replace all accessible plastic coolant components at once. Total cost for a comprehensive coolant system refresh including hoses and connectors typically runs €400-800 at a specialist. Aftermarket aluminium replacement connectors are available for the most failure-prone locations.
Valve cover gasket leaks
up to €1,0006 of 8
Gaskets on both valve cover banks harden and leak oil onto exhaust manifolds · more· less
The V8 has two valve covers (one per bank) and both gaskets are prone to hardening and leaking as the engine ages. Oil seeps onto the exhaust manifolds, producing a distinct burning smell and visible smoke from the engine bay. This is a common issue on virtually all high-mileage B7 S4s. Parts cost €50-100 for both gaskets. Labor is moderate but requires removing the intake manifold for access to one side, which adds complexity. Total repair cost is typically €400-600 at an independent shop or €700-1,000 at an Audi dealer.
Dual mass flywheel failure (manual gearbox)
up to €1,5007 of 8
Internal springs in the DMF weaken and break, causing rattling from the bellhousing · more· less
This issue only affects manual gearbox cars. The dual mass flywheel absorbs driveline vibration but the internal springs can weaken and break over time, particularly on cars driven aggressively or with aftermarket tunes. Symptoms include a rattling or chattering noise from the bellhousing area, especially at idle and low RPM. The flywheel costs approximately €400-600 for an OEM part, with aftermarket options available. Labor requires gearbox removal (6-8 hours), so replacing the clutch at the same time is recommended. Total cost for DMF and clutch replacement is typically €1,200-1,500 at an independent specialist. Tiptronic automatic cars do not have this issue.
ZF Tiptronic solenoid and mechatronic wear (automatic only)
up to €2,5008 of 8
Transmission solenoids and internal seals degrade, causing harsh shifts and delayed engagement · more· less
The ZF 6HP19 Tiptronic automatic is generally robust but requires regular fluid and filter changes that many owners neglect. When the internal solenoids degrade or the mechatronic seal between the controller and case fails, symptoms include delayed gear engagement, harsh or jerky shifts, and eventually limp mode. Audi's period schedule only called for leak checks, while ZF recommends an oil change after 150,000 km and sooner under demanding use. A transmission fluid and filter service costs €200-300. There is no routine solenoid replacement interval. Solenoid replacement costs €800-1,200, while a full mechatronic unit repair can reach €2,000-2,500. ZF introduced updated green ATF (G060162A2) that helps prevent some of these issues. Manual gearbox cars are not affected.
Rewarding V8, but timing chain service is the defining ownership cost
The B7 S4's 4.2L V8 is a characterful engine that can reach high mileages when properly maintained, but it carries one of the most expensive known service requirements in its class. The timing chain and tensioner service dominates the ownership cost picture, and whether this has been completed is the single most important factor when buying. Beyond that, oil consumption, control arm wear, and typical V8 maintenance items add up. Cars with documented timing chain service and consistent maintenance records are significantly less risky than those without. The manual gearbox is more engaging but adds DMF as a concern; the Tiptronic is reliable when serviced correctly.
Service history
Complete Audi dealer or specialist records essential. Verify oil changes every 10,000-15,000 km with quality oil.
Cold start
Must start engine completely cold. Listen for any rattling in the first 30 seconds. This is the most important single test.
Test drive
Minimum 30 minutes including varied speeds. Check for smooth power delivery, no warning lights, and correct gear changes.
Oil level and condition
Check dipstick before and after test drive. The 4.2 V8 takes 9.5 litres. Low oil or very dark oil suggests neglected maintenance or excessive consumption.
Specific for this vehicle
Listen for cold start rattle (timing chain)
Start the engine completely cold. Any rattling lasting more than 2-3 seconds indicates worn timing chain tensioners. A loud, sustained rattle means the chain service is urgently needed. This single test can reveal a €3,500-6,000 repair.
Ask for timing chain service records
Request documentation proving the timing chain, tensioners, and guides have been replaced. If no records exist on a car with over 100,000 km, budget for preventive replacement.
Check oil consumption history
Ask the owner how much oil they add between services. More than 1 litre per 2,000 km is concerning. Look for blue smoke on startup and under hard acceleration.
+ 4 more checksShow less
Inspect front suspension for play
Jack up the front and check each control arm for play. Listen for clunking over bumps during the test drive. Budget for a full control arm kit if the car has over 100,000 km and originals.
Check coolant system for leaks
Inspect all visible plastic connectors, T-pieces, and elbows in the cooling system. Look under the car for coolant stains. Check coolant level and expansion tank condition.
Test all electrical systems
Check all windows (regulators are known to fail), sunroof operation, climate control, and instrument cluster. Scan with VCDS for stored fault codes.
Verify gearbox type and condition
Manual: listen for flywheel rattle at idle. Tiptronic: check for harsh shifts and ask whether the transmission fluid has ever been changed, since ZF calls for it after 150,000 km and sooner under hard use.
Ignition coils on the longitudinal 4.2 MPI BBK checked and replaced, Audi service campaign 28E9 of 19 November 2010 for export markets (service campaign, not a safety recall)Verify completed
The Takata airbag recall is the most critical safety item affecting B7 S4 models, and service campaign 28E9 of 19 November 2010 had the BBK ignition coils checked and replaced in export markets. Contact an Audi dealer with the VIN to verify all recalls and service campaigns have been completed. The airbag replacement is free of charge regardless of vehicle age.
Warranty Status
Factory warranty (2 years)Expired on all B7 S4 models
Rust perforation warranty (12 years)Expired on all B7 S4 models
Recall repairsFree regardless of warranty status
All Audi S4 B7 models are well outside any factory or extended warranty coverage. Budget for all repairs out of pocket. Third-party warranty providers may offer limited coverage but typically exclude known problem areas like timing chains and oil consumption on vehicles of this age.
Sources: Research draws on model-specific owner forums and owner communities, recall information from official authorities, German automotive press, and multiple workshop cost references cross-checked against each other.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.
