2011-2018 · 1.6L M270 turbocharged petrol (122 hp)
Practical family MPV with Mercedes badge appeal. The M270 engine is generally reliable but needs regular oil changes to prevent timing chain and turbo issues. The 7G-DCT dual-clutch automatic is the weak point - many owners report jerky shifts and expensive failures, especially if transmission oil hasn't been changed. Manual gearbox versions are significantly more reliable. Budget for thermostat replacement (expensive labor), potential carbon buildup cleaning, and suspension bushings. Better reliability than the W245 predecessor. Inspections show this generation has above-average reliability with only 4.8% defect rate at 6 years old.
Jerky shifts, delayed engagement, and mechatronics failures common without proper oil changes · more· less
The 7-speed 7G-DCT is the weak point of the B-Class. Over 70% of faulty gearboxes had never had an oil change in 100,000 km. Common issues include jerky shifts (especially in stop-go traffic), delayed engagement when shifting from Park to Drive, and sudden lurching between 1st and 2nd gear. The dual-mass flywheel on diesel models is particularly vulnerable. Early cars needed firmware updates to improve shift quality. Symptoms include warning messages "Reverse gear not available", fault codes like 092177 (shift valve position error), and clunking noises when engaging P/N/R. Replacement costs €3,000-4,000 at dealers, €1,500-2,500 at specialists. Manual gearbox B-Class models avoid this issue entirely.
Timing chain and tensioner wear€1,200 - €2,500
Chain stretches around 80,000-120,000 km, causes cold start rattle for 1-30 seconds · more· less
The M270 engine's timing chain typically lasts 80,000-130,000 km (±20,000 km). The tensioner has a release valve that weakens over time, allowing oil pressure to bleed overnight. This causes distinctive rattling on cold starts - anything over a few seconds indicates wear. The rattling disappears once oil pressure builds. If ignored, the chain can skip teeth and cause catastrophic valve-to-piston contact. Complete replacement includes timing chain, guides, tensioner, and sprockets. Parts cost €400-600, but labor is 8-12 hours due to engine position. Independent specialists charge €1,200-1,800 total; dealers €2,000-2,500. Always use OEM Mercedes parts. Regular oil changes with correct spec oil (MB 229.xx) and avoiding only short trips significantly extends timing chain life.
Thermostat housing failure€700 - €1,400
Dealer-only part requiring significant disassembly, fails around 70,000-100,000 km · more· less
The M270 engine's thermostat is an expensive dealer-only part integrated with the electric water pump housing. It typically fails between 70,000-100,000 km. Symptoms include coolant warning light, engine not reaching operating temperature (stays below 80°C after 10-15 minutes driving), poor cabin heating, or overheating. The car should reach 80°C within 10 minutes of urban driving from cold, and 90°C+ within 15 minutes. The part costs €250-350 but labor is 6-9 hours due to accessibility in the tight engine bay - dealers quote €700-1,400 total. Independent Mercedes specialists may charge €800-1,000. This is a known M270 weak point affecting all models with this engine (A-Class, CLA, GLA, B-Class).
Carbon buildup from gentle driving causes limp mode, EPC warning light · more· less
The turbo actuator tends to stick if the car is driven too gently or only for short trips, as carbon builds up on the mechanism. Symptoms include EPC (Electronic Power Control) warning light, sudden limp mode with reduced power, and poor throttle response. Mercedes won't sell the actuator separately from the turbocharger assembly. Actuator-only cleaning/repair at specialists costs €500-700. If turbo internals are damaged from oil starvation or foreign object damage, full turbocharger replacement costs €800-1,500 (parts €500-1,400, labor 2-4 hours). Turbo lifespan is typically 150,000-180,000 km with proper maintenance. Prevention: use premium fuel, regular spirited driving to clear carbon, and ensure correct MB-spec synthetic oil is used.
Suspension bushings and shock absorbers€400 - €1,200
Clunking noises over bumps, worn control arm bushings and top shock mounts · more· less
Noisy suspension is one of the most frequently reported problems. Drivers hear clunking or knocking when driving over uneven roads or speed bumps. The most common cause is failed top shock absorber bushings, causing metal-to-metal contact. Control arm bushings deteriorate with age, becoming softer and allowing excessive suspension movement. This leads to uneven tire wear, poor handling, and braking instability. Rear shock absorbers should be replaced in pairs for balanced rebound. Replacement bushings are often not included with new shocks. Front shock absorbers with bushings cost €150-250 per pair, rear €120-200 per pair. Control arm bushings add €200-400. Labor for full suspension refresh is 4-6 hours. Total costs: €400-800 at independents, €800-1,200 at dealers.
Carbon buildup on intake valves€800 - €1,500
Direct injection engines accumulate carbon, cleaning needed around 100,000+ km · more· less
The M270 uses direct injection which sprays fuel directly into the cylinder, meaning fuel never washes over the intake valves. Over time, oil vapor from the PCV system bakes onto the valve backs, reducing airflow and causing rough idle, hesitation, and reduced power. Carbon buildup becomes significant after 100,000 km. Professional walnut shell blasting is the most effective cleaning method, costing €1,000-1,500. Chemical cleaning via fuel rail is cheaper (€400-600) but less thorough. DIY cleaning takes 3+ hours per bank. Prevention: regular oil changes with high-quality synthetic oil, occasional highway drives at higher RPM, and fuel system cleaners like Chevron Techron (Mercedes-approved). Some owners report improvement with regular Italian tune-ups (sustained high-RPM driving).
Camshaft adjuster solenoid failure€800 - €3,000
Solenoid/adjuster failures cause engine noise, typically around 60,000-80,000 km · more· less
Camshaft adjuster problems on M270/M274 engines manifest as ticking, knocking, or clattering noises from the engine bay due to improper valve timing. This issue affects various Mercedes models (A-Class, B-Class, C-Class, CLA) around 60,000-80,000 km. The solenoid itself is inexpensive (€50-100 each x2), but replacement requires significant disassembly. Labor costs are high: independent specialists charge €800-1,200, dealers €2,000-3,000 for both banks. Mercedes has issued specific repair instructions. In severe cases where the adjuster mechanism itself is damaged, costs can exceed €4,000 because the engine may need to be removed. Some specialists offer adjuster regeneration services as a more affordable alternative. Using correct oil specification and regular changes helps prevent premature failure.
Tailgate lock actuator failure€200 - €600
Corroded contacts from water ingress, tailgate won't lock or unlock · more· less
Electrical failures of the tailgate locking system particularly affect W246 models. Water can leak into the tailgate from the rear washer hose, damaging electrical components including the lock actuator, handle, and wiper motor. Symptoms include tailgate not responding to key fob, failing to lock/unlock, or only opening but not locking. The actuator can push but not pull when broken. Water damage can also corrode wiring harnesses. Diagnosis requires removing the tailgate trim panel. The actuator part costs €100-200, with 1-2 hours labor. If wiring or other components are damaged, costs increase to €400-600. Prevention: inspect rear washer connections for leaks, ensure tailgate seals are intact.
Excessive oil consumption€800 - €3,000
Some engines consume 1L per 1,000-2,000 km due to worn rings/seals · more· less
While not as common as on some competitors, some B180 owners report excessive oil consumption requiring top-ups between services. Owners report consumption of 1 liter per 1,000-2,000 km, which is technically within Mercedes spec but concerning. Causes include worn piston rings (more common with hot engine/high RPM), valve stem seals (evident on cold starts), or turbocharger seals. Blue smoke from exhaust indicates oil burning. Diagnosis: valve seal issues show symptoms on cold start and deceleration; piston ring issues worsen with hot engine and high RPM. Valve seal replacement costs €800-1,200 at specialists (worth it according to owners). Piston ring replacement requires engine teardown (€2,000-3,000). Turbo seal replacement €500-800. Regular oil level checks are essential. Some owners find oil consumption disappears after valve seal replacement.
Better than predecessor, but DCT gearbox is major concern
The W246 B-Class is significantly more reliable than the W245 it replaced. Official inspection data shows only 4.8% defect rate at 6 years old (vs 9.2% average). The M270 engine is generally dependable with proper maintenance - timing chain and thermostat are the main engine concerns. However, the 7G-DCT dual-clutch automatic transmission is problematic, with over 70% of failures linked to lack of transmission oil changes. Manual gearbox versions are dramatically more reliable. Budget for regular oil changes, transmission servicing if DCT-equipped, and likely suspension refresh around 100,000 km.
Pre-Purchase Inspection Checklist
General checks
Service history
Complete Mercedes dealer or specialist service records essential. Verify oil changes at correct intervals with MB-approved oil.
Tires
Common sizes: 205/55R16 or 215/55R16. Check tread depth (minimum 3mm), age (date codes), and uneven wear patterns.
Cold start
CRITICAL: Engine must be completely cold. Listen carefully for rattling in first 30 seconds - timing chain indicator.
Body condition
Check for accident damage, rust, panel gaps. Hungarian build quality is generally good.
Test drive
Minimum 20 minutes including highway speeds to get transmission and engine fully warm.
Specific for this vehicle
Cold start timing chain rattle test
Start engine completely cold. Listen for rattling/chattering for first 30 seconds. Any rattle lasting more than 2-3 seconds indicates timing chain/tensioner wear. This is THE most important check.
7G-DCT transmission behavior (if automatic)
Drive at least 15 minutes in varied conditions. Feel for jerky shifts, hesitation, clunking when selecting P/N/R, delayed engagement Park to Drive. Check for "Reverse gear not available" warnings. Verify transmission oil has been changed (should be every 60,000-80,000 km). Manual gearbox is FAR more reliable.
Engine temperature test
On cold day, engine should reach 80°C within 10 minutes urban driving, 90°C+ within 15 minutes. If stays below 80°C, thermostat has failed (expensive repair).
Check for EPC warning light
Drive car spiritedly. If EPC light appears with power loss, indicates turbo actuator issues.
Suspension noise check
Drive over speed bumps and rough roads slowly. Listen for clunking from suspension - indicates worn bushings or shock absorber mounts.
Tailgate function test
Test tailgate lock/unlock multiple times with key fob. Check for water stains inside tailgate trim (remove if possible) - indicates washer hose leak damaging lock actuator.
Oil consumption check
Check engine oil level - should be between min/max. Ask seller about oil consumption between services. Inspect for blue smoke from exhaust on cold start or acceleration.
Verify recall completion
Contact Mercedes with VIN to verify all recalls completed, especially: power steering malfunction (2014), driveshaft retaining rings (2012-2013), starter overload (2015-2017), steering column grounding/airbag (2012-2017).
Recalls and Technical Service Bulletins
Power steering malfunction (2014 models)TSB LI46.35-P-059241
Driveshaft retaining rings breakage (Sep 2012 - Jun 2013)Verify completed
Interior fuse box loose fuses (Sep - Nov 2014)Verify completed
Front passenger airbag deployment (Oct - Dec 2016)Verify completed
Starter overload/overheating (Jan 2015 - Jan 2017)Verify completed
A total of 21 recalls were issued for the W246 B-Class, which is disappointing for Mercedes. Contact a Mercedes-Benz dealer with the VIN to verify all recalls and TSBs have been completed. The steering column airbag recall (2018) is particularly important.
Warranty Status
Factory warranty (2 years)Expired on all 2011-2018 models
7G-DCT extended warranty (if purchased)Check with Mercedes dealer
Corrosion warranty (30 years)Still active with service history
All W246 B-Class models are now outside their original factory warranty. Some dealers offered extended warranties on the 7G-DCT transmission due to known issues - check if this was purchased and is still valid. The 30-year corrosion warranty remains valid if the car has complete Mercedes service history. Independent warranty coverage is available from third-party providers.
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.