Legendary performance sedan with AMG's 4.0L twin-turbo V8. More reliable than the previous 6.2L M156, but still a specialist car with high running costs. The M177 engine is generally robust when maintained properly, though watch for excessive oil consumption, carbon buildup on direct injection valves, and ignition coil failures between 60,000-100,000 km. Interior rattles are common but mostly cosmetic. The 9-speed MCT transmission is generally reliable but can develop slippage issues, especially when tuned. C63 S models with electronic differential face expensive repairs if the diff fails. Not a cheap car to run, but one of the best-sounding and most engaging performance sedans of its generation.
Expected Annual Maintenance Costs
€2,100 - €3,800/year
15,000 km/year
Fixed costs
€1,200-2,000
Risk buffer
€900-1,800
What Can Break
bars = likelihood
Excessive oil consumption€200 - €3,500
M177 engine can consume 1 liter per 1,000 km, may require piston rings or valve seals · more· less
One of the most frequently reported issues with the M177 engine. Many owners report burning more oil than expected, with some averaging a quart of 0W-40 every 1,000 km. Mercedes-Benz often states this is "completely fine" for high-performance engines. Regular oil changes with manufacturer-recommended oil (0W-40 or 5W-40) can help reduce consumption. If the issue persists and consumption is excessive, it may require replacing piston rings or valve seals, which involves significant labor costs. Always check oil level regularly and top up as needed. Some owners report that switching from 0W-40 to 5W-40 helped reduce consumption slightly.
Carbon buildup on intake valves€800 - €1,500
Direct injection engines don't clean valves naturally, needs walnut blasting every 50,000-80,000 km · more· less
The M177 uses direct fuel injection, which injects fuel directly into the combustion chamber. This means intake valves don't get the "cleaning" effect of fuel passing over them, leading to carbon deposits over time. This is common in all modern direct-injected engines. Symptoms include rough idle, loss of power, and poor fuel economy. Periodic intake valve cleaning via walnut blasting is recommended every 50,000-80,000 km to remove carbon buildup and restore engine performance. Cost varies: dealers may charge €1,200-1,500, while independent specialists charge €800-1,000. Some owners report Mercedes has improved the design compared to earlier direct-injection engines, but all will eventually need this service.
Ignition coil failures€200 - €800
Known defect in M177 ignition coils, typically fails between 60,000-100,000 km · more· less
Ignition coil defects are more common in AMG C63 models and can cause misfiring, loss of power, and check engine lights. This often occurs between 60,000-100,000 km. Symptoms include rough running, poor acceleration, and illuminated engine warning light. Each coil costs approximately €60-100, and labor is around €100-250 depending on whether you replace one or all eight. Some owners report cold start misfires on early cars (cylinders 1 and 6), which can be resolved with a software update. If coils fail and cause misfires, unburned fuel can permanently damage the catalytic converter from overheating, so address immediately. Replacing coils early can prevent subsequent damage.
Interior rattles and squeaks€0 - €500
Dashboard, door panels, and trim commonly rattle, especially in cold weather · more· less
One of the most commonly reported issues on the W205 C63. Owners report squeaks and rattles from driver door/window area, dashboard (particularly gauge cluster), speakers, center console, door trims, and various interior panels. The noise is often temperature-dependent and worse in cold weather. Mercedes-Benz has acknowledged these issues but dealers struggle to find and fix them permanently. Some owners have had components replaced under warranty (screens, trim pieces), but rattles often return. DIY fixes include applying felt tape to trim contact points and securing loose clips with super glue. Not a safety issue but annoying on a premium car. Build quality concern rather than mechanical failure.
Turbocharger failure€5,000 - €8,000
Twin turbos can fail between 100,000-150,000 km, engine removal required · more· less
The M177's twin-turbo setup is key to its impressive performance, but turbochargers are wear items. Average lifespan is 100,000-150,000 km under normal use, though harsh driving or inadequate maintenance can accelerate wear. Symptoms include loss of power, difficulty maintaining high speeds, slower acceleration, grey/blue exhaust smoke, and rattling/scraping noises. Cost is extremely high because the engine must be removed to access the turbos. Parts cost approximately €4,500-5,000, with 16-18 hours of labor at dealer rates. Some dealers quote up to €8,000 total. Related issues include turbocharger oil line leaks (€700-800 to fix) and boost sensor failures (€170-220). Regular oil changes with high-quality oil are critical to turbo longevity.
MCT transmission slippage€2,000 - €6,000
9-speed MCT wet clutch can slip, especially below 3,500 rpm or when tuned · more· less
The Mercedes-AMG Speedshift MCT 9-speed transmission uses a wet multi-clutch pack instead of a torque converter. Some owners report slippage when driving at constant speed around 2,000 rpm - the RPM slips 100-200 rpm in every gear when accelerating gently. The problem disappears with harder acceleration. This is more common on modified/tuned vehicles. The MCT clutch may open and close momentarily, causing the slip. Diagnosis is difficult because a faulty MCT often doesn't throw fault codes. Symptoms include delayed gear changes, slippage (especially in first and second gear), and the need to warm up the gearbox before smooth shifting. Solutions range from software updates (TCU recalibration) to clutch pack replacement or full transmission rebuild. Regular transmission and differential fluid changes help prevent issues.
Electronic differential failure (C63 S only)€5,000 - €8,000
C63 S e-diff can fail, especially when tuned or launched repeatedly · more· less
The C63 S uses an electronic locking differential (e-diff), while the non-S has a mechanical limited-slip differential. The e-diff is an expensive component and there's no direct aftermarket replacement. Symptoms include whining noise (especially on throttle), groaning at low speeds when turning, and metallic debris in differential fluid. Some owners report failures around 20,000-25,000 km, particularly on US market cars that are tuned for high power or frequently launched. When differential fluid is drained, it often contains metal flakes indicating internal wear. Mercedes dealers quote approximately €8,000 for replacement. Rebuild options exist through specialists like Premier Tuning Group for less, but you need to find someone willing to work on it. Regular differential oil changes and avoiding aggressive launches help prevent failure.
Engine mount failure€1,000 - €1,300
Fluid-filled mounts fail, causing excessive vibration especially at idle · more· less
The C63 has four engine mounts that support the 4.0L V8. Factory mounts are fluid-filled for comfort but can fail prematurely, especially under the stress of 500+ hp and aggressive driving. When the rubber fails, the fluid leaks out and the mount becomes useless. Symptoms include excessive engine vibration (even at idle), vibrations in the cabin or steering wheel, rough idling, and clunking sounds during acceleration or gear changes. Engine mounts typically last 100,000+ km but can fail earlier on hard-driven cars. Replacement cost is €1,000-1,300 for all four mounts including labor. Some owners upgrade to upgraded solid or polyurethane mounts for improved longevity and performance, though these transmit more vibration to the cabin.
Water pump / thermostat failure€1,400 - €2,200
Typically fails between 70,000-100,000 km, often replaced together · more· less
The M177 engine's water pump and thermostat are common failure points between 70,000-100,000 km. Symptoms include coolant warning light, engine overheating, poor cabin heating, and visible coolant leaks. The M177 engine already runs hot, so cooling system failures must be addressed immediately to prevent engine damage. Water pump replacement costs €1,400-1,700 on average. It's recommended to replace the thermostat at the same time since labor is the biggest cost component (6+ hours). Some shops offer combined water pump and thermostat replacement for €1,800-2,200. Completely flushing the cooling system during replacement is also recommended. If belts or hoses are worn, expect additional costs. Regular coolant level checks help catch issues early.
Brake squeal€0 - €600
Known issue with AMG brake pads, Mercedes says it's "normal" for performance brakes · more· less
Brake squeal is a known issue on the W205 C63 AMG that Mercedes-Benz has acknowledged. Dealerships state it's attributed to the brake pad compound used (no asbestos) and is "normal" for high-performance brakes. Squealing typically occurs from the front brakes during light braking when slowly coming to a stop. Some owners have had brakes replaced under warranty, but the noise often returns after a few hundred miles. There is a TSB on retainer clips causing squeaking. Attempted fixes: flushing brake assemblies with water (temporary), applying anti-squeal paste (not recommended by AMG), replacing with aftermarket pads like EBC Red/Yellow Stuff (€100-150), or switching from ceramic to semi-metallic pads. Not a safety issue but annoying. Resurfacing pads with 80-grit sandpaper and re-bedding can help.
Timing chain stretch€900 - €2,500
Rare on M177, but listen for cold start rattle; chains designed to last engine life · more· less
Unlike timing belts, the M177's timing chain is designed to last the life of the engine. However, factors such as poor oil quality, infrequent oil changes, and high-stress driving can lead to premature wear and stretching. Symptoms include unusual rattling sounds from the engine (especially at cold startup), loss of power, poor fuel economy, and engine misfires. The noise of a stretched chain is typically very loud in the first few seconds after cold start, then calms down. Chain tensioners can also fail, allowing slack in the chain. If approaching 100,000+ km, have the chain and tensioners inspected by a Mercedes-AMG specialist. Timing chain tensioner replacement costs €900-1,100, while full timing chain replacement (chain, guides, tensioners, sprockets) costs €2,000-2,500 due to high labor. Much less common on M177 compared to older Mercedes engines.
More reliable than previous C63, but specialist maintenance required
The W205 C63 with its M177 engine is significantly more reliable than the W204 C63 with its infamous M156 head bolt issues. The M177 is generally robust when maintained properly with high-quality oil and regular servicing. Most issues are age-related (mounts, pumps, seals) or characteristic of high-performance turbocharged engines (oil consumption, carbon buildup). Interior quality concerns like rattles are frustrating but not mechanically significant. Budget for specialist AMG maintenance and set aside €1,500-2,500 annually for unexpected repairs.
Pre-Purchase Inspection Checklist
General checks
Service history
Complete Mercedes-AMG dealer or authorized specialist records essential. Verify oil changes every 10,000-15,000 km maximum with correct 0W-40 or 5W-40 specification.
Tires
Check tread depth, age (date codes), and uneven wear. Rear tires wear faster. Run-flat tires are expensive (€1,200+ for set).
Cold start
Must start engine completely cold. Listen for timing chain rattle, rough idle, or misfires in first 30 seconds.
Body condition
Check for accident damage, paint mismatch. These are high-performance cars - accident history is critical.
Test drive
Minimum 30 minutes including highway speeds. Transmission needs to be fully warm to show issues.
Specific for this vehicle
Check engine oil level and consumption history
Ask owner about oil consumption. Check dipstick - should be at maximum when cold. Oil level 1L low after 1,000-2,000 km is common but borderline excessive.
Test drive for 20+ minutes, check for transmission slippage
Drive in Sport mode around 2,000 rpm at constant speed. Feel for RPM slipping 100-200 rpm when accelerating gently. Check for delayed shifts or jerky gear changes.
Listen for ignition coil misfires
During test drive, feel for hesitation, rough running, or check engine light. Ask if coils have been replaced (common around 60,000-100,000 km).
Check for interior rattles (drive over bumps)
Drive over rough roads and speed bumps. Listen for dashboard rattles, door panel squeaks, gauge cluster noises. Nearly all W205s have some rattles.
Inspect differential for leaks and noise (C63 S: e-diff)
On C63 S, listen for whining under throttle or groaning when turning at low speeds. Check underneath for differential leaks. Ask if differential oil has been changed.
Check for brake squeal
During test drive, brake gently from low speeds. Listen for squealing from front brakes. This is common and not a safety issue but annoying.
Verify recalls completed (VIN check)
Contact Mercedes-Benz with VIN to verify all recalls completed: seatbelt buckle switches (June-Oct 2018), front seat frame welds (June 2017-June 2018), steering coupling locknut, differential mounting flange (aggressive launch recall).
Check coolant level and condition
Low coolant or brown/milky appearance indicates water pump, thermostat, or head gasket issues. M177 runs hot - cooling system health is critical.
Inspect engine mounts for failure
Start engine and watch for excessive movement or vibration. Fluid-filled mounts leak when they fail. Vibration at idle suggests worn mounts.
Check for carbon buildup symptoms
Ask if intake valves have been walnut blasted. Rough idle, loss of power, or poor fuel economy at 50,000+ km suggests carbon buildup.
Fuel pump impeller degradation (2021-2023 models)Check with dealer
Contact Mercedes-Benz with VIN to verify all recalls completed. The rear differential mounting flange recall (software update) is particularly important for C63 S models. Some recalls don't expire as long as Mercedes remains in business.
Warranty Status
Factory warranty (2 years unlimited km)Expired on all W205 C63s
Extended warranty (1-3 years)€1,500-3,000/year
All W205 C63s (2015-2021) are now outside factory warranty. Extended warranty is available through Mercedes-Benz dealerships but expensive (€1,500-3,000 per year depending on coverage level). Given annual repair costs average €1,200+, extended warranty may not be cost-effective unless you get comprehensive coverage. Independent specialists often provide better value than dealer servicing.
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.