2007-2014 · 1.6L/1.8L M271 Kompressor & CGI petrol
A popular entry-level Mercedes sedan with decent build quality and low running costs for the segment. The W204 generation marked a quality improvement over the W203. The M271 engine (both 1.6L Kompressor and 1.8L CGI variants) is generally durable but requires attention to timing chain tensioner issues, especially after 80,000 km. Early models (2007-2009) are particularly prone to electronic steering lock (ESL) failure. The 7G-Tronic transmission conductor plate is a known weak point. Post-2010 models are more reliable after Mercedes addressed early issues. Best suited for buyers who maintain proper service intervals and aren't deterred by occasional German car complexity.
Expected Annual Maintenance Costs
€900 - €1,700/year
15,000 km/year
Fixed costs
€500-850
Risk buffer
€400-850
What Can Break
bars = likelihood
Timing chain tensioner wear€1,000 - €3,000
Tensioner loses pressure overnight causing cold start rattle from 80,000 km · more· less
The M271 engine's timing chain tensioner has a release valve that weakens over time, allowing oil pressure to bleed off overnight. This results in a distinctive rattle for 1-30 seconds on cold starts, typically appearing between 60,000-100,000 km. Problems usually start around 80,000 km on W204 models. If rattle lasts more than a few seconds, the chain, guides, tensioner, and sprockets all need replacing. Ignoring this warning leads to chain skip and catastrophic valve-piston contact. The CGI turbo variant typically gives adequate warning with noise, while the Kompressor version can fail more suddenly. Independent shop: €1,000-1,800; dealer: €2,000-3,000. VW has released an updated tensioner part. Some vehicles exceed 250,000 km with original parts, suggesting the actual failure rate may be lower than forum discussions suggest.
Motor wears out after 8-10 years, preventing engine start; 2007-2009 models most affected · more· less
The ESL commonly fails after 8-10 years due to worn brushes on the worm drive motor. Most affected are 2008-2009 W204s from a bad batch. Symptoms include intermittent steering unlock, clicking noise from column, or complete failure where car won't start, steer, or shift out of park. If you need to insert the key multiple times for steering to unlock, ESL failure is imminent. ESL emulator bypass (no steering lock, compromises security): €350-500 installed. Repair services (mail-in): €400-500. OEM dealer replacement with programming: €1,500-2,000. The emulator solution is most popular as it eliminates the faulty motor entirely while keeping the CAN bus happy.
Speed sensors fail in conductor plate causing harsh shifts or limp mode · more· less
The 722.9 7G-Tronic automatic transmission conductor plate (TCM) breaks down internally, preventing correct monitoring of input shaft speed. This causes ineffective torque converter lock-up, resulting in rough/jerky gear changes or stuck in 2nd gear (limp mode). Early 722.9 transmissions (2004-2008, designated VGS1) had highest failure rate. Problems can start as early as 50,000 miles. There are three VGS versions (1, 2, 3) - not interchangeable. VGS1 requires both valve body and conductor plate replacement (€2,500-3,500); VGS2/3 can replace conductor plate only. New OEM conductor plate: €1,000+ plus programming at dealer (required as it's theft-relevant). Third-party repair services: €100-300 plus reinstall labor (€400-600), no programming needed. Can temporarily reset by turning off engine for 10 seconds.
Rear subframe corrosion€0 - €5,000
Rusts from inside out, especially salt-treated regions; 20-year warranty if perforated · more· less
W204 rear subframes rust from the inside, particularly severe in regions with road salt. Mercedes extended warranty to 20 years/unlimited miles for rear subframe, but only covers perforation (holes). Surface rust without holes doesn't qualify. Original issue affected cars up to 2013. Owners in snowy regions most affected. Some 2009 models with 45k miles had serious rust on PAS pipes and undercarriage. Check interior door panels (bottom of passenger doors) for rust spots. If not covered by warranty: used subframe €400-800 + €500-1,000 labor; dealer replacement €3,000-5,000. Diagnosis fee at dealer: €250-300 (waived if subframe rot confirmed). Reimbursement available for already-paid repairs if perforation existed. Wash undercarriage regularly in salt regions; consider anti-rust treatment.
Front control arm bushings wear€400 - €1,000
Hydro bushings crack and split causing clunking, typical life 50,000-80,000 km · more· less
Despite redesigns from failure-prone W203, W204 bushings still crack and split, causing popping/clunking when wheels turn. Typical bushing life approximately 50,000-80,000 km, though can vary widely (some fail at 90,000 km, others last 180,000 km). If bushing has torn or ruptured, surrounding area may be wet with fluid. Visual inspection on rack is difficult as play doesn't show when wheels hang unsprung. Symptoms: loose front end feel, clunking over bumps, vibration at highway speeds. Rubber parts exposed to weather last about 10 years. Complete Lemförder control arms (not OEM) are more economical than pressing in new bushings due to labor. Always replace in pairs. Independent: €400-700 parts + labor; dealer: €800-1,000+.
Water pump / thermostat housing failure€600 - €1,400
Electric water pump integrated with thermostat typically fails 70,000-100,000 km · more· less
The M271 engine uses an electric water pump integrated with thermostat housing that commonly fails between 70,000-100,000 km. Symptoms: coolant warning light, engine overheating, poor cabin heating. The thermostat has built-in heater and electronic components making it expensive. Parts cost: €150-400. Thermostat is under engine on left side, requires significant dismantling. System must be drained and refilled. Independent garage: €600-800 total; dealer: €1,000-1,400. DIY possible but allow 4 hours minimum for first attempt. Water pump failure also common on OM651 diesel variants. Check coolant level and condition - low or brown/milky appearance indicates problems.
SAM module water ingress€300 - €1,800
Signal Acquisition Module corrosion from water causes electrical gremlins · more· less
SAM modules are usually very reliable unless they get wet. Water/liquid damage leads to corrosion and eventual failure. W204 has 4-5 SAM units depending on complexity. Symptoms: various warning lights, non-functioning lights/wipers, brake lights stuck on, electrical gremlins. Front SAM is in engine compartment driver-side control box. If original unit is cleaned/repaired, no programming needed. If replaced with new unit, programming at Mercedes dealer required. Clean original SAM with rubbing alcohol and brush (not always successful). Investigate and fix water source. Repair services: €300-500; new SAM from dealer: €800-1,000 + programming; total dealer replacement: €1,200-1,800. DIY cleaning or used refurbished units reduce costs considerably.
AC compressor seizure€900 - €1,800
Early models prone to compressor failure from lack of lubrication · more· less
AC compressors on early W204 models are prone to seizure, typically after 60,000-70,000 miles but varies with use. Causes: refrigerant leaks (seals/hoses), clogs in valves/filters/condensers, lack of lubrication causing friction and heat damage, electrical failure, seized piston. Symptoms: warm air from vents, squealing/grinding noise, belt may come off if bearing fails. Most Mercedes C300 (W204) compressor replacements cost €1,200-1,800. Remanufactured unit: €900; new OEM: €1,300+. Complete evacuation of AC system required. Serpentine belt, refrigerant lines, electrical connectors must be removed. Give system complete diagnostic before replacing compressor. While driveable with failed compressor, grinding from pulley indicates bearing failure risk - belt may detach.
Carbon buildup on intake valves (CGI direct injection)€300 - €1,500
Direct injection engines accumulate carbon from PCV vapors, recommend cleaning 60,000-100,000 km · more· less
M271 EVO CGI engines with direct injection (post-2009) have no fuel washing intake valves. Carbon builds from PCV oil vapors mixing with EGR gases. Only affects direct injection variants, not Kompressor. Symptoms: rough idle, loss of power, hesitation. Walnut-shell blasting recommended around 60,000-100,000 km. Walnut blasting (intake manifold removal): €1,200-1,500. Chemical cleaning service: €300-500 (less effective). CRC GDI cleaner (spray through intake): €50-100 (removes up to 46% deposits). Prevention: use low NOACK volatility synthetic oil, occasional highway runs, premium fuel, Chevron Techron cleaner (Mercedes-approved). DIY cleaning possible: 3 hours with carb cleaner, drill with zip ties, manual scraping. Kompressor engines don't have this issue as port fuel injection washes valves.
Headlight condensation€50 - €3,400
Fogging occurs in humid conditions due to ventilation design; Mercedes considers normal · more· less
W204 headlights fog up in wet/humid conditions. Mercedes considers this normal as headlights are ventilated for heat dispersal (not fully sealed). Particularly common with discharge gas bulbs. LED headlights fog more as they don't generate enough heat to evaporate moisture. Sometimes caused by poorly installed rear plastic cover trapping wires. Solutions: Run headlights during drive - should clear naturally. Silica gel pack inside bulb access cover (permanent fix for many). Remove headlight, blow-dry moisture, apply silicone around all creases. Mercedes OEM fix: special thick lid with desiccant bag. One-way breather valve with long hose. Dealer replacement: €3,400 for complete assembly (often not covered under warranty as Mercedes doesn't recognize as fault). DIY fixes: €50-200. If moisture doesn't clear after driving, have dealer inspect for warranty consideration.
Decent reliability for a German premium sedan with diligent maintenance
The W204 C180 is generally reliable when properly maintained, marking a quality improvement over the W203. Most issues are well-documented and give warning signs. Early models (2007-2009) have higher ESL failure rates. Post-2010 models are safer bets after Mercedes addressed initial problems. The M271 engine is fundamentally sound but requires attention to timing chain condition from 80,000 km onward. Budget €900-1,700/year for routine maintenance plus occasional repairs. Independent specialists can significantly reduce costs versus dealership service.
Pre-Purchase Inspection Checklist
General checks
Service history
Complete Mercedes dealer or authorized specialist records essential. Verify oil changes at proper intervals (max 15,000 km). Extended intervals cause timing chain issues.
Tires
Check tread depth, age (date codes on sidewall), uneven wear patterns. Standard sizes: 205/55R16 or 225/45R17.
Cold start - CRITICAL
Must start engine completely cold. Listen carefully for timing chain rattle in first 30 seconds. Any rattle indicates tensioner/chain issues requiring immediate attention.
Body condition
Check for rust on rear subframe (lift car), wheel arches, bottom of doors. Avoid Mars Red paint (moisture issues). Check boot area near release handle.
Test drive
Minimum 20 minutes including varied speeds. Listen for clunking from suspension over bumps. Test AC function. Feel for transmission harshness.
Specific for this vehicle
Electronic steering lock operation
Insert key and feel for smooth steering unlock. Try multiple times. Listen for clicking noise from steering column. If inconsistent unlocking or clicking present, ESL is failing. Particularly important on 2007-2009 models.
Transmission operation (7G-Tronic)
Drive for 15+ minutes to warm transmission. Feel for harsh/jerky shifts, slipping, or stuck gears. Check for limp mode (stuck in 2nd gear). Confirm no transmission warning lights. Conductor plate issues common on early transmissions.
Rear subframe inspection
Lift vehicle and inspect rear subframe thoroughly for rust/corrosion. Check if already replaced under warranty. Surface rust without perforation not covered by extended warranty. Critical for cars from salt-treated regions.
Front suspension clunking
Drive over bumps slowly and listen for clunking/popping from front. Turn wheel lock-to-lock while stationary - listen for noise. Indicates worn control arm bushings - common issue but not dangerous, just annoying and requires repair.
Engine variant identification
Confirm if 1.6L Kompressor, 1.8L Kompressor, or 1.8L CGI (turbocharged, post-2009). CGI gives better warning of timing chain issues. 1.6L has slightly fewer reported issues than 1.8L. Check engine code M271.
SAM module electrical function
Test all lights (headlights, indicators, brake lights, interior). Test wipers. Check for any random warning lights. Check for water in footwells. SAM failure causes various electrical gremlins.
Coolant system
Check coolant level and condition. Look for leaks around water pump/thermostat housing (left side under engine). Low coolant or brown/milky appearance indicates issues. Common failure point 70,000-100,000 km.
AC operation
Test air conditioning - should blow cold within 2 minutes. Listen for unusual noises from engine bay when AC engaged. Early models prone to compressor seizure.
Check for oil leaks
Inspect valve cover, oil cooler, camshaft adjuster magnets for oil seepage. Common M271 issue but usually minor if caught early.
Recalls and Technical Service Bulletins
Crankshaft position sensor (OM642 diesel, 2006-2007)Verify if applicable
Power steering fluid leak (June 2009 - Feb 2010 production)Verify completed
Fuel filter leak (C320/C350 CDI diesel, Nov 2009 - July 2011)Verify if applicable
Oil leak from timing chain tensioner (OM651 diesel, 2014)Verify if applicable
Takata airbag inflator (various production dates)Verify completed
Contact a Mercedes-Benz dealer with the VIN to verify all recalls and technical service bulletins have been completed. The C180 petrol variants are not affected by diesel-specific recalls, but power steering and airbag recalls may apply depending on production date.
Warranty Status
Factory warranty (2 years/unlimited km in EU)Expired on all W204s
Rear subframe corrosion warranty20 years/unlimited km (perforation only)
All 2007-2014 W204 C180s are outside original factory warranty. Mercedes extended rear subframe warranty to 20 years/unlimited miles, but only covers perforation (holes in metal). Surface corrosion without holes does not qualify. Extended warranty packages available from third-party providers - review exclusions carefully as items like oil leaks and wear items are typically not covered.
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.