The last great naturally aspirated V8 sedan. A 6.2-liter hand-built AMG engine with 457 hp and one of the best exhaust notes ever. This is a muscle car in a business suit - brutally fast, outrageously thirsty (12-20 mpg), and expensive to run. Early cars (pre-2011, engine #60657 or lower) suffer from head bolt corrosion causing coolant-oil contamination and engine failure - verify repair completed or budget €3,000-10,000. Camshaft adjuster wear affects 2007-2010 models. Rear tires last 5,000-15,000 km depending on driving style. The 2012+ facelift with MCT transmission is more reliable. Already appreciating - well-maintained examples are future classics.
Head bolt corrosion and failure (pre-2011)€3,000 - €10,000
Head bolts corrode and snap, mixing coolant with oil - engine #60657 or lower affected · more· less
This is the most serious M156 engine issue. From 2007-2010, Mercedes used head bolts with a female head design that exposed raw metal to corrosion. As the bolt corrodes and loosens, coolant mixes with engine oil creating brown sludge. When the bolt snaps, major head gasket failure follows. Symptoms include low coolant warnings, misfires, coolant in oil, and check engine light. Typically occurs after 90,000 miles. Mercedes updated to male-top head bolts starting with engine serial #60658 (mid-2011 production). Repair costs €3,000-10,000 depending on damage - some owners report quotes of €7,000-9,000 just for labor and gaskets. If buying pre-2011, verify head bolt update completed or negotiate €5,000 off purchase price. Failure rate approximately 1.7% of affected engines.
Rear tire wear (consumable but extreme)€300 - €550
Rear tires last 5,000-15,000 km - budget €300-550 per pair every year · more· less
This is inevitable with 600 Nm going to the rear wheels. Owner reports: Pirelli P Zero rears completely bald after 6,000 km of spirited driving, Continental Sport Contact lasting 8,000-13,000 km, Michelin Pilot Sport 4S providing best longevity at 12,000-15,000 km. OEM sizes are 235/35R19 front, 255/30R19 rear (or 235/40R18 / 255/35R18). Premium rear tires cost €250-280 per tire fitted in Europe. Front tires last 2-3x longer. If you drive 15,000 km/year, expect 1-2 rear tire changes annually depending on driving style. Budget €300-550/year minimum for rear rubber.
Camshaft adjuster wear (2007-2010)€4,500 - €6,500
Soft metal camshafts wear prematurely causing ticking, reduced performance · more· less
A class action lawsuit in 2011 claimed Mercedes knew about M156 camshafts, lifters, and bearings wearing out prematurely due to improperly heat-treated soft metal. Symptoms include ticking/knocking noises from engine bay, rough idle, and reduced performance. Mercedes issued service bulletin in 2007 for upper engine noise inspection. Dealer replacement costs €5,000-6,500 including labor in Europe. Important: replacement camshaft adjusters are not improved - many owners report noise returns within 10,000-15,000 km as new adjusters start wearing. Primarily affects early 2007-2010 production. Listen carefully for any ticking on cold start during test drive.
Cam position sensor oil leak into wiring harness/ECU€100 - €10,000
Oil wicks through sensor connectors into ECU - catastrophic if ignored · more· less
The camshaft position sensors don't just leak externally - oil travels through the electrical connector down the wiring harness to the ECU, MAF, and O2 sensors. Symptoms include multiple fault codes for oxygen sensors, ignition coils, and other auxiliary sensors appearing simultaneously. Mercedes dealers quote full wiring harness + ECU + sensor replacement at €10,000+. DIY solution: install sacrificial pigtail harnesses (€100 in parts) between sensors and main harness - when sensors leak, you replace cheap pigtails instead of €2,000 harness. Many specialists clean the ECU with contact cleaner and gravity-drain oil, then install new sensors with pigtails for under €500 total. Catch this early or face catastrophic repair bills.
Brake wear (aggressive driving)€800 - €2,500
Heavy car with serious performance - brakes work hard · more· less
OEM pricing from Mercedes dealers: front pads €516, front rotors €1,088 each, rear pads €382, rear rotors €343 each. Full OEM brake job at dealer: €3,500-4,000. Aftermarket alternatives significantly cheaper: Brembo rotors €600-800 per axle, quality pads (Pagid/Jurid/EBC) €200-300 per axle. Complete aftermarket front and rear job runs €1,200-1,700 at independent shops. Performance Pack models have expensive 2-piece rotors - you can retrofit standard C63 rotors to save money. Typical lifespan: front pads 30,000-50,000 km, rear pads 40,000-60,000 km, rotors 60,000-80,000 km depending on driving style. Track use accelerates wear dramatically.
7-speed MCT can be jerky, overheat, or slip in higher gears · more· less
The 2012+ facelift introduced the AMG Speedshift MCT 7-speed multi-clutch transmission. While generally reliable, common issues include: jerky/rough shifting especially in stop-start traffic (some owners report this is normal characteristic), transmission overheating during spirited driving causing limp mode, slipping in 4th-7th gears (reported at 100,000+ km), and premature clutch pack wear. Mercedes techs confirm MCT is "joltier" than torque converter auto and not as smooth. Software updates can improve shifting. Mechatronics unit failures cost €2,500-3,500 at dealers. Pre-facelift cars with 7G-Tronic torque converter automatic are smoother but slower shifting. Manual gearbox (rare) is most reliable option.
Engine mounts failure€700 - €1,300
Fluid-filled mounts wear causing vibration, clunking when shifting · more· less
Factory Mercedes W204 C63 engine mounts are fluid-filled for comfort but lack longevity under the M156's power and torque. Symptoms include excessive vibration felt in cabin/steering wheel especially at idle, clunking/bumping noises when shifting gears, loud knock when reversing from driveway, movement visible in engine bay during acceleration, and oil leaking from failed mount. Typical lifespan 80,000-120,000 km. Mercedes dealer cost €1,000-1,300 for both engine and transmission mounts. Aftermarket polyurethane mounts (Kreissieg, Creative Steel) cost €400-600 and last longer but transmit more vibration. DIY possible but tight engine bay makes it difficult - budget 4-6 hours labor.
Differential and subframe bushings€600 - €1,200
Rubber bushings perish causing creaking, poor handling, subframe movement · more· less
W204 differential and rear subframe bushings can fail prematurely, especially on AMG models with higher torque loads. Symptoms include creaking when shifting from Drive to Reverse, rattles and squeaks over bumps, wheel tramp under hard acceleration, and vague rear-end handling. OEM rubber bushings are soft for comfort but allow excessive subframe movement under load. Mercedes dealer quoted £770 (€900) for diff mount bushings replacement. Polyurethane aftermarket bushings (K-MAC, Creative Steel) improve handling but cost €400-700 plus labor. Important: some W204s suffer rear subframe corrosion/cracking - inspect thoroughly. Mercedes has replaced subframes free of charge in some corrosion cases.
Valve cover gasket oil leaks€300 - €1,400
Left valve cover leaks oil onto exhaust causing burning smell, smoke · more· less
Common M156 engine issue - valve cover gaskets leak with age, particularly the left side (driver's side US). Oil drips onto hot exhaust manifold causing burnt oil smell in cabin and visible smoke. Labor-intensive repair due to V8 packaging - warranty time is 13.1 hours but many shops charge 15-20 hours. Parts cost €150-250 for gasket sets. Total cost €300-500 at independent specialists, €1,000-1,400 at Mercedes dealers. Some owners report leaks recurring after 50,000-70,000 km suggesting OEM gasket quality issues. Inspect carefully during pre-purchase - look for oil residue on valve covers and smell for burnt oil.
ESP/ABS module failure€200 - €2,000
Internal control unit fault causes ABS, ESP, power steering warnings · more· less
Common failure of W204 ABS/ESP module (control unit N30/4) causes multiple warning lights: ABS, ESP, "Power steering malfunction", and "Run Flat Indicator inoperative". Diagnostic codes 5001, 5944, 5945 indicate internal ABS module fault. New module from Mercedes costs €1,800-2,000 plus coding. Better solution: specialist repair services rebuild your original module for €200-600 with 12-month warranty - no coding required since it's your original unit. Labor to remove/install is minimal (10-15 minutes). Some UK dealers quoted £1,180 fitted for new unit. Module is part of ABS hydraulic unit under hood.
Modern Mercedes engines use plastic thermostat housings that can crack or warp from heat cycling. Symptoms include coolant leaks at housing, overheating, poor cabin heating, and coolant warning lights. On some models the thermostat is integrated with housing and must be replaced as complete unit. Parts cost €150-300. Mercedes dealer replacement €900-1,100, independent specialists €550-750. DIY-friendly repair requiring only basic tools and 2-3 hours. Important: inspect housing for corrosion during replacement - corroded housing prevents proper hose sealing and may fail again quickly. Clean mounting surfaces thoroughly before installing new gasket.
M156 V8 has individual ignition coils for each cylinder. Coils typically last vehicle lifetime but fail when spark plugs are overdue for replacement - excess resistance from worn plugs stresses coils. Symptoms include check engine light, rough running, misfires on specific cylinder. Cost €200-320 at independent shops, €250-325 at dealers. Cylinders 1-2 are easy 45-minute jobs, cylinders 7-8 require removing fuel lines and other components (3 hours). Mercedes issued product recall in 2018 on some coil part numbers. Current updated part number is A1779060206. Pro tip: replace spark plugs on schedule (60,000-80,000 km) to prevent premature coil failure.
Alternator failure€600 - €1,900
Alternator can fail around 100,000+ km - labor-intensive replacement · more· less
Alternators typically last 100,000+ km but can fail earlier with frequent short trips or high electrical loads. Symptoms include dimming headlights, battery warning light, dead battery despite recent replacement, and electrical system malfunctions. Mercedes dealer cost €1,250 for alternator plus €650 labor = €1,900 total. Aftermarket alternators available from €230-400. Sometimes only voltage regulator needs replacement (€500-700). W204 C63 alternator replacement is labor-intensive - radiator support and cooling fan must be removed, sway bar mount bolts accessed from underneath, oil cooler lines bolted to bottom alternator bolts make reinstallation difficult. Budget 4-6 hours labor at independent shop for total €600-900.
High-performance means high-maintenance
The C63 W204 is reasonably reliable for a 457 hp performance car, but ownership costs are substantial. Early models (2007-2010) have serious head bolt and camshaft issues that can cause engine failure. The 2012+ facelift with updated engine internals and MCT transmission is significantly more reliable. Budget €2,500-5,500 annually including extreme tire wear, premium fuel, and periodic major repairs. This is not a car for budget-conscious buyers - but for enthusiasts who accept the costs, the naturally aspirated M156 V8 experience is priceless and likely to appreciate.
Pre-Purchase Inspection Checklist
General checks
Complete service history essential
Full Mercedes dealer or specialist records required. Verify oil changes every 10,000-15,000 km with MB 229.5 spec oil.
Cold start inspection
Must start engine completely cold. Listen carefully for any ticking, rattling, or knocking for first 30 seconds.
Extended test drive
Minimum 30 minutes including highway speeds to get transmission fully warmed up. Feel for harsh shifting or transmission issues.
Tire condition and age
Check date codes on tires. Expect rear tires to be significantly more worn than fronts. Budget for replacement.
Professional pre-purchase inspection at Mercedes specialist
Do not use generic inspection service. C63 has specific issues only Mercedes specialists know. Budget €200-450 for thorough PPI.
Specific for this vehicle
Verify head bolt update on pre-2011 models
If engine serial number is #60657 or lower, confirm head bolt repair completed. Request documentation. If not done, negotiate €5,000 off purchase price or walk away.
Listen for camshaft adjuster ticking on cold start
Start completely cold. Any ticking/rattling noise indicates camshaft adjuster wear (€4,500-6,500 repair). More than 2-3 seconds of noise is serious concern.
Check for cam position sensor oil leaks
Inspect cam position sensors for oil residue. Check wiring harness connectors for oil contamination. This can lead to €10,000 ECU replacement if ignored.
Inspect rear subframe for rust/corrosion
Get car on lift and thoroughly inspect rear subframe, especially on cars from regions with road salt. Subframe cracking/corrosion is known W204 issue.
Test steering lock (ESL) multiple times
Insert key and listen for click 5-6 times. ESL failure prevents engine starting - common W204 problem.
Check for valve cover oil leaks
Inspect both valve covers for oil seepage. Smell for burnt oil. Look for oil residue on exhaust manifolds.
Verify all recalls completed
Use VIN to check with Mercedes for steering column ground recall (2013-2014 models) and any other outstanding campaigns.
Inspect brake condition thoroughly
Check pad thickness and rotor condition. Performance Pack cars have expensive 2-piece rotors. Budget €800-2,500 for brakes if worn.
Check service history for transmission fluid changes
MCT transmission (2012+) requires fluid service. Verify completed or factor into purchase price.
Test all electronics and check for multiple fault codes
Multiple unrelated codes (O2 sensors, ignition coils, MAF) may indicate oil in wiring harness from cam sensors.
Contact Mercedes-Benz with VIN to verify all recalls completed. Head bolt issue was never officially recalled despite widespread failures - verify repair documentation on pre-2011 cars.
Warranty Status
Factory warranty (2 years)Expired on all W204 C63s
Typical coverage exclusionsWear items, high-mileage cars (120,000+ km)
All W204 C63 AMGs are outside original factory warranty. Extended warranties available from third parties but often exclude major known issues like head bolts and camshaft wear. Read fine print carefully. Many specialists recommend self-insuring with dedicated repair fund instead.
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.