Mercedes-Benz E 400
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 Convertible W213 — Modern and Refined
333 hp BiTurbo in the new E convertible: more modern infotainment, better materials, same driving feel. The M276 BiTurbo works here as in its predecessor — responsive, powerful, sonorous. The new fabric hood is lighter than the metal folding roof of the W212. Visually the most elegant E 400 — for those who want the BiTurbo V6 open-top in more modern packaging.
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 16
An incorrectly routed gearbox wiring harness allows water ingress with an increased fire risk. Mercedes issued a recall.
Following software updates, the ECU in individual C238 units was permanently damaged. One owner reported a seven-month workshop stay.
A serial design defect: the tension cables in the soft-top headliner fray and snap after approximately 200–300 roof cycles. Mercedes revised the design from May 2020.
The electric parking brake generates fault messages and seizes, particularly in cold weather. Grinding noises when applying indicate worn components.
The soft-top tension cords fray after just a few hundred opening cycles. A design fault that led Mercedes to carry out goodwill repairs.
At higher mileages the electric motors in the roof kinematics or the hydraulic unit can fail. The roof can then no longer open or close fully.
Brake discs on the W213 show juddering after just a few thousand kilometres. Individual cases report renewed juddering after warranty replacement.
Elevated MOT failure rates at suspension mounts. The double wishbone front axle shows wear at bearings and joints.
Infotainment and driver assistance systems are prone to faults. Brake assist and cruise control warning messages appear without cause. Often resolved via software update.
The electric parking brake is prone to corrosion and seizing. Multiple recall actions for the brake system have been documented.
The electric parking brake generates fault messages and seizes, especially in cold weather. Grinding and creaking noises when releasing are common.
The optional Airmatic air suspension is prone to compressor and air bag failures. Replacement requires removal of the rear axle and is expensive.
The headliner tension cords fray and snap after approximately 200–300 roof cycles. Design fault present until the facelift in 05/2020. Mercedes repair approx. 1,200 EUR, upholstery shop approx. 300 EUR.
The rotary push controller on the centre console is mechanically fragile and shows signs of failure after heavy use.
MBUX system freezes or reboots. Bluetooth connections drop, voice control unresponsive. Software updates only fix some issues.
Hollow-section seals at the side window frame collect rainwater. When the door is opened the collected water runs onto the seat. Particularly with the Easy Entry function.