Mercedes-Benz AMG C 43 Cabrio
Four-valve V6 in two basic variants: 3.5L naturally aspirated (DES 35, 185–225 kW) with direct injection and stratified charge — refined, linear, no classic naturally aspirated feel. And the 3.0L BiTurbo family (DEH 30 LA, 245–295 kW) with Nanoslide coating, twin turbochargers and water-air charge air cooler. The BiTurbo sings sonorously from 2,500 rpm and screams at the top — exceptional for a V6. Weak points: timing chain wears early when oil change intervals are pushed. Oil cooler in the V-block doesn't seal forever. Camshaft solenoids leak. On the 3.5L stratified-charge variant add NOx sensor failures from short-trip use. Early DES 35 (2011–2013) had piston slap issues. The BiTurbo unit with Nanoslide is considered more robust. Maintained with short oil change intervals (10,000–12,000 km) the engine easily lasts beyond 200,000 km.
V6 BiTurbo cabriolet — the C43 sounds best with the top down
270 kW BiTurbo without a roof is the best C43 experience. The V6 sounds beautifully sonorous from 2,500 rpm and turns into a wail above that — straight into the ear with the roof open. All-wheel drive for year-round use, soft top for spontaneous sunny days. Rarer than the saloon and estate, more character than both. For anyone who wants the AMG V6 sound in the open air — the moments one does not forget.
Engine Weaknesses 10
Known weak point: the oil cooler gasket in the V-block of the M276 ages and starts leaking. Repair is extremely labour-intensive because the engine must be partially disassembled — cost €1,700–3,800.
Symptoms: Oil spots under the vehicle, rainbow sheen on wet road, dropping oil level, oil smell
Known damage pattern on all newer Mercedes engines: solenoid valves leak, oil migrates into the wiring harness. First the lambda sensors die, then the ECU. Repair documented up to €1,970.
Symptoms: Check engine light with camshaft fault code, lambda sensor failure, oil film on connectors, in extreme cases ECU failure
On early M276 DES 35 (build years 2011–2013) pistons can loosen due to cylinder bore wear. Knock noise on cold start, worst case engine damage.
Symptoms: Clacking and knocking on cold start from the engine area, getting louder over time, rough idle when cold
The two-stage chain drive system of the M276 receives insufficient oil on early engines, leading to premature chain wear.
Symptoms: Rattling on cold start, rough idle, in the worst case chain jump
The M276 has a plastic thermostat housing that cracks with age and loses coolant. The thermostat itself can also fail open.
Symptoms: Coolant loss, puddle under the vehicle, fault code P0128, engine runs too cold on motorway, temperature gauge fluctuates
The M276 PCV system with oil separator is known for failures from defective membranes or blocked valves. Increased oil consumption and power loss from false air ingestion.
Symptoms: Noticeably rising oil consumption, blue smoke from exhaust, crankcase breather fault code P052E, power loss
On the M276 DES 35 (stratified-charge variant) the NOx sensors in the exhaust stream fail. Moisture accumulates at the sensor — short-trip driving prevents it from burning off. Repair costs €900–1,200 per sensor.
Symptoms: Check engine light, NOx sensor fault code, possibly increased fuel consumption and harder starting
The exhaust manifold can crack from thermal shock — especially on sportily driven examples and early build years. Welding repair is possible but not lasting.
Symptoms: Unusually loud exhaust note, power loss, exhaust smell in the engine bay or cabin, incorrect lambda sensor readings
On M276 BiTurbo variants, the wastegate linkage on the turbochargers can develop play and rattle. A progressively louder metallic noise from the turbo area. Turbocharger replacement required.
Symptoms: Metallic clattering and rattling from the engine area, especially under load, gets worse over months, boost pressure fault code
Direct injection on the M276 V6 causes carbon deposits on the intake valves. Cleaning is necessary at higher mileages.
Symptoms: Stumble when accelerating from part throttle, rough idle, slight increase in fuel consumption
Vehicle Weaknesses 9
Longitudinal members, jack-point attachment holes and rear axle subframe rust through. MB offers goodwill replacement.
Polycarbonate blind cover of the panoramic roof incorrectly bonded. When opening, the blind can come loose. Recalled by MB.
Ball joints on the wheel-side wishbone and rubber-metal bushes wear. New suspension geometry makes repairs more involved.
Some W205 models discharge the battery unusually quickly during extended parking. Cause: elevated quiescent current draw from control units.
The W205 shows above-average front axle issues from the second MOT onwards according to TÜV statistics. Worn control arms and drop links are the main causes.
W205 A/C fails with 'Air conditioning off' without a fault code in the onboard computer. Often the compressor or A/C control unit is defective.
Panoramic roof on the W205 creaks when opening and closing. Guide linkage can bend and jam the roof. Repair often requires complete removal.
The tensioning cables of the convertible hood inner lining fray through mechanical friction and tear. Approximately 1 cm gap remains when closing. Mercedes repair approximately €2,700, 50% goodwill possible.
With a wet roof, water collects in the door frame seal profiles of the side windows. When the door is opened, the collected water runs onto the seat. Problem more pronounced with Easy Entry function.
Reports & Tests
1503 owner complaints filed with NHTSA (2014–2021). Most reported: Engine (402), Other (235), Airbags (219).