Mercedes-Benz B180 W246

The Getrag 7G-DCT (724.0) dual-clutch transmission in the B180 is prone to jerking at low speeds, vibrations between 20 and 40 km/h, and clutch slippage when hot. Problems typically surface between 70,000 and 120,000 km, especially on cars used primarily in urban traffic. Industry data suggests over 70% of faulty gearboxes had never received an oil change in the first 100,000 km. Diesel models tend to fail earlier due to higher torque loads, but petrol B180s are also affected. A clutch pack replacement costs approximately 900-1,400 with aftermarket parts, up to 2,000 with OEM components. A mechatronics repair runs 1,200-3,000. Regular oil changes every 60,000 km significantly reduce the risk. Manual gearbox variants are unaffected by this issue entirely.

The M270 1.6 engine uses a timing chain that can stretch prematurely, particularly on early 2011-2014 models. The tensioner loses hydraulic pressure overnight, producing a distinctive metallic rattle for a few seconds on cold start. This typically begins between 100,000 and 150,000 km. Mercedes released updated tensioner parts (A2700501147 for the camshaft adjuster). If the rattle persists beyond a few seconds, the chain, guides, tensioner, and sprockets all need replacing. Parts cost 150-400 depending on quality, but labor is substantial due to the transverse engine layout. Total replacement runs 900-1,800. Ignoring this issue risks catastrophic valve-piston contact. Regular oil changes at intervals shorter than the factory 25,000 km schedule help extend chain life significantly.

The M270 uses an electronically controlled thermostat housing that is located at the bottom of the engine, making access difficult. Failure typically occurs between 60,000 and 100,000 km. Symptoms include the temperature gauge not reaching normal operating temperature (should sit between 95 and 105 degrees via OBD2), poor cabin heating in winter, or intermittent overheating warnings. The OEM part costs approximately 150-200, and labor runs 3-4 hours due to the thermostat's buried position. Total cost at an independent shop is 400-600, or 600-800 at a Mercedes dealer.

A common M270 issue where the valve cover gasket degrades after 80,000-120,000 km and begins leaking oil onto the exhaust manifold, producing a noticeable burnt oil smell from the engine bay. While not immediately dangerous, the oil can contaminate nearby components and create a fire risk if left unaddressed long-term. The gasket itself costs 30-60 for aftermarket or 80-120 for OEM. Labor is 1.5-2 hours. Total cost is 200-400 depending on the shop.

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, a reset via the diagnostic tool resolves the problem. 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.

A known W246-specific issue where the main relay in the power circuit fails, causing a complete loss of electrical power. The relay is located in an unusual position under the floor near the gear shifter, which makes it susceptible to moisture and corrosion. Symptoms are sudden and complete: no dashboard, no ignition, no response from any controls. The relay itself costs 40-80, but diagnosis and access can add considerable labor time. Total repair cost is 150-400 depending on whether the root cause is simply the relay or involves corroded wiring.