The W246 B-Class is Mercedes-Benz's compact MPV, sharing its MFA platform with the A-Class W176 and CLA C117. The B200 CDI pairs the proven OM651 turbodiesel with either a 7G-DCT dual-clutch automatic or a 6-speed manual, delivering strong fuel economy around 4.5 l/100 km. Pre-facelift cars (2012-2014) use a 1.8L variant, while post-facelift models (2014-2018) use the 2.1L version, both producing 136 hp and 300 Nm. Mercedes dropped the CDI suffix in September 2015, so the same car is sold as B200 CDI up to that point and as B200 d afterwards; this report covers both.· more· less
Proven OM651 diesel, very durableSpacious interior with high seating
7G-DCT gearbox can be costlyDiesel emissions system upkeep
Buy if: You drive long distances regularly and can find one with a manual gearbox or a DCT with documented transmission oil changes.
Avoid if: You mostly make short urban trips (DPF and EGR clogging) or the car has a 7G-DCT with no transmission oil change records.
Price & maintenance
Used price
€11,000
median asking price, typically 145,000 km
Typical range€8,500 – €13,500
Maintenance cost
€800 – €1,600/year
at 15,000 km/year
Fixed costsservice, tyres, brakes€500 – €900 /yr
Risk bufferunplanned repairs€300 – €700 /yr
Price estimates are based on German asking prices. Prices and costs vary by vehicle condition and location.
Ownership costs
Maintenance assumes 15,000 km a year. Price estimates are based on German asking prices. Prices and costs vary by vehicle condition and location.
Clutch pack and mechatronics wear, worsened by the OM651's diesel torque in city driving · more· less
The 7G-DCT (724.0) dual-clutch gearbox is the most common complaint across all W246 diesel models. It is a Mercedes design with wet, hydraulically operated clutches, not the separate Getrag 700.423 used elsewhere in the range, and the OM651's 300 Nm of torque puts significant stress on the clutch packs. Symptoms include jerking at low speeds, vibrations between 20-40 km/h, hesitation when pulling away, and clutch slippage when hot. Problems typically appear between 70,000-120,000 km, especially on cars used predominantly in city traffic. Over 70% of faulty gearboxes reportedly never had an oil change in the first 100,000 km. Daimler service information specifies a gearbox oil service at 100,000 km with MB 236.21 specification fluid, so this is not a lifetime fill; specialists often shorten that interval on city-driven cars. A clutch pack replacement costs approximately 900-1,400 with aftermarket parts, 1,500-2,000 with OEM. Mechatronics repair or replacement runs 1,200-3,000. A TCU software adaptation reset (100-200) can improve shift quality in early-stage symptoms. Manual gearbox variants are entirely unaffected.
DPF clogging from short-trip driving
€400 - 2,0002 of 6
Diesel particulate filter fails to regenerate on short urban journeys, causing limp mode · more· less
The DPF on the OM651 requires the engine to reach full operating temperature and sustain approximately 2,000 rpm at 60+ km/h for regeneration. Cars used primarily for short urban trips accumulate soot beyond the point where passive regeneration is possible. Symptoms include the DPF warning light, reduced power, limp mode, and increased fuel consumption during failed regeneration attempts. A forced regeneration at a workshop costs 100-200. Professional off-car cleaning costs 300-500. Complete DPF replacement costs 1,200-2,000 including the catalytic converter section. The differential pressure sensor can also fail, preventing regeneration even on highway-driven cars (sensor replacement: 150-250). Regular motorway driving of at least 30 minutes per week significantly reduces the risk. Check the engine oil level before buying: if it is significantly above the maximum mark, diesel has been contaminating the oil from failed regenerations.
The OM651 uses a single-row (simplex) timing chain rather than a more durable duplex chain. This was acknowledged by Mercedes when the successor OM654 switched to a duplex design. The chain is located at the rear of the engine, making replacement labor-intensive. Symptoms begin as a distinctive metallic rattle for 1-5 seconds on cold start as the tensioner loses hydraulic pressure overnight. This typically starts between 120,000-180,000 km with proper oil changes, but can occur earlier with neglected maintenance. Mercedes has revised the tensioner multiple times. Parts for the full chain kit cost 200-400, but labor is substantial as the engine may need to be partially lifted. Total replacement cost is 1,000-1,800 at an independent specialist, 1,800-2,500 at a Mercedes dealer. Ignoring the rattle risks chain skip and catastrophic valve damage. Regular oil changes at 10,000-15,000 km intervals (rather than the factory 25,000 km) significantly extend chain life.
EGR valve and intake manifold carbon buildup
€350 - 9004 of 6
Carbon deposits restrict airflow, causing rough idle, hesitation, and reduced power · more· less
Like most modern diesels, the OM651 accumulates carbon deposits in the EGR valve and intake manifold over time. Symptoms include rough idling, hesitation under acceleration, black smoke, and increased fuel consumption. The EGR valve can stick open or closed. Cleaning the EGR valve and intake manifold costs 200-400 at a specialist. Full EGR valve replacement runs 350-900 including the part (150-400) and labor. The EGR cooler can also develop internal leaks, allowing coolant into the intake tract and causing white smoke on cold starts. EGR cooler replacement costs 400-800. Regular highway driving and quality diesel fuel help reduce buildup. Cleaning interval recommendation is every 80,000-120,000 km.
Fuel filter housing coolant leak
€250 - 5005 of 6
Coolant seeps from the fuel filter housing where it connects to the cylinder head · more· less
The OM651 fuel filter housing has coolant passages running through it and bolts to both the cylinder head and inlet manifold. Under boost pressure, the inlet manifold flexes, stressing the housing seals. This causes a slow coolant leak that can be difficult to pinpoint as it often drips internally rather than pooling visibly. Symptoms include gradually dropping coolant level with no obvious external leak, and sometimes a sweet smell from the engine bay. Mercedes released an updated housing design (part A6512003900). The replacement part costs 80-150, but the repair requires removing the EGR cooler and replacing its gasket as well, bringing total repair to 250-500 at an independent shop.
Electronic parking brake malfunction
€300 - 7006 of 6
Parking brake becomes stuck or shows malfunction warning, requiring actuator repair · more· less
Several W246 owners report the electronic parking brake becoming stuck or displaying a malfunction warning on the dashboard. The issue can be caused by a faulty actuator motor, corroded cables, or a software glitch in the control module. In some cases, holding the parking brake switch for 10+ seconds and restarting the engine resolves the problem. Lubricating the parking brake mechanisms with penetrating lubricant can also help. When the actuator itself needs replacement, costs run 300-700 including parts and labor. The issue is more common on cars that have had little use or have been stored for extended periods.
Proven diesel engine, but emissions equipment and gearbox need attention
The OM651 diesel is one of Mercedes' most durable modern engines, with many examples exceeding 250,000 km. However, ownership costs are driven by the diesel emissions equipment (DPF, EGR) and the 7G-DCT dual-clutch gearbox, which suffers under the engine's torque with city driving. Manual gearbox versions are considerably more reliable. Pre-2014 cars have an additional concern with the timing chain tensioner. Post-2014 facelift models are generally the better buy. The B-Class avoids the water ingress issue that plagues the W176 A-Class. Short oil change intervals (10,000-15,000 km rather than the factory 25,000 km) and keeping to the 100,000 km gearbox oil service are the most effective preventive measures.
Service history
Complete Mercedes dealer or specialist records essential. Verify oil changes at correct intervals with MB 229.51 specification oil.
Tires
Check tread depth, age (date codes on sidewall), and uneven wear patterns. Standard size is 205/55R16.
Cold start
Must start the engine completely cold. Listen for metallic rattling (timing chain) and watch for excessive white or blue smoke (injectors/EGR cooler).
Test drive
Minimum 20 minutes including city and motorway driving. Pay attention to gearbox behavior, boost delivery, and any warning lights.
Specific for this vehicle
Cold start chain rattle and exhaust smoke
Start the engine completely cold. A metallic rattle lasting more than 2-3 seconds indicates timing chain tensioner wear. White smoke after warm-up suggests EGR cooler leak or injector problems.
7G-DCT gearbox test in traffic
If automatic: drive in stop-start conditions for at least 10 minutes. Watch for jerking when pulling away, vibrations at 20-40 km/h, or warning messages. Ask when gearbox oil was last changed.
Check coolant level and condition
Low coolant without visible external leak suggests fuel filter housing or EGR cooler leak. Check the coolant expansion tank level and look for signs of frequent topping up.
+ 2 more checksShow less
Check DPF status and driving history
Ask about typical driving patterns. Short-trip-only cars will have DPF issues. If possible, read the DPF soot loading via OBD2. Check engine oil level for overfilling from failed regenerations.
Test the electronic parking brake
Apply and release the electronic parking brake several times. Verify no warning messages appear on the dashboard and the brake engages and releases smoothly.
Recalls and Technical Service Bulletins
Timing chain tensioner seal ring oil leak and fire hazard (2014 OM651 diesel models)Verify completed
Brake booster vacuum hose failure - loss of power braking (April 2011 - January 2015 production, OM651 left-hand-drive cars)Verify completed
Starting current limiter overheating - fire risk (build window is VIN-dependent, confirm with a dealer)Verify completed
High pressure fuel line can crack - fuel leak and fire risk (W246 four-cylinder diesels built October 2015 - January 2019)Critical - verify completed
Mandatory KBA diesel emissions software update (Euro 5 OM651 models produced before August 2014); separate voluntary service measures exist and are VIN-specificVerify completed
Front passenger seat occupant classification fault (January - February 2018 production)Verify completed
Contact a Mercedes-Benz dealer with the VIN to verify all recalls have been completed. The steering column grounding recall is particularly important as it can cause inadvertent airbag deployment. Build windows quoted for this car online often come from other markets and do not match the European scopes, so ask for a VIN-based printout rather than judging from the build year.
Warranty Status
Factory warranty (2 years)Expired on all W246 models
Rust perforation warranty (30 years)May still apply on newer W246s
Extended warrantyAvailable through Mercedes dealers and third parties
All W246 B200 CDI models are outside their original 2-year Mercedes-Benz factory warranty. Extended warranty packages are available through Mercedes dealers and independent providers. The 30-year rust perforation warranty may still apply depending on the car's registration date.
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.
