Mercedes-Benz AMG CLE 53
Return to the inline-six after years of the M276 V6 — and the difference is immediately noticeable. Smoother, more even rev build-up, torque plateau from 1,600–4,000 rpm without any weakness. The 48V mild-hybrid system with integrated starter-generator (ISG) is not a marketing term: 16 kW of boost on pull-away fills turbo lag completely; measurable fuel saving in sail mode. When buying, check the 48V battery — failure costs 2,000–4,000 EUR, primarily affecting build years up to 2022. Electric coolant pumps can fail from 80,000 km. Change oil every 10,000 km, do not rely on Longlife — HPFP and camshaft adjusters are sensitive to old oil. Cold-start wastegate bushing rattle is by design and not a fault. Overall a very accomplished engine that holds 250,000 km without issues when maintained correctly.
AMG Inline-Six Without a Roof — the Most Emotive M256
330 kW open-top — the CLE 53 Cabriolet is the most emotionally charged M256 vehicle of all. Hood down, AMG exhaust, inline-six soundtrack straight to your ears. Nearly V8 character without V8 consumption. The rarest and most desirable of the entire M256 range. If you want a modern AMG convertible that doesn't sound like a four-cylinder: this is it.
Engine Weaknesses 9
Frequently reported problem: 48V battery of the EQ Boost system fails and costs 2,000–4,000 EUR to replace. Design issue with earth connection in early vehicles.
Symptoms: EQ Boost deactivated, start-stop system failed, hybrid warning light, sporadic starting problems
The known Mercedes problem of leaking camshaft solenoids also affects the M256 (same solenoid technology as M276/M270). Oil migrates by capillary action and destroys lambda sensors and the ECU.
Symptoms: Lambda sensor fault codes, MIL, rough running. Multiple electrical faults simultaneously as it progresses
M256 shows elevated oil consumption from approx. 100,000 km, attributable to the PCV system and cylinder walls. Regular oil level checks necessary.
Symptoms: Dropping oil level, occasional bluish smoke after warm-up phase
The beltless M256 operates exclusively electric coolant pumps. Pump motors fail internally and trigger temperature warnings. Bleeding requires specialist diagnostic equipment.
Symptoms: Coolant temperature warning, irregular operating temperature, occasional overheating warning
The camshaft-driven high-pressure pump on the M256 can wear prematurely with irregular oil changes. Injectors can be damaged by metal debris.
Symptoms: Fuel pressure fault codes, rough idle, starting problems, hesitation under load, elevated fuel consumption
With predominantly short-trip use the OPF cannot fully regenerate. Power drop and elevated consumption result. Virtually no risk for motorway drivers.
Symptoms: Power drop at higher load, elevated fuel consumption, occasional particulate filter warning, engine runs rougher
The M256 uses Camtronic variable valve actuation — same technology as M276/M270 with documented failures. Wear on the adjustment unit or solenoid valve is possible. Oil quality is decisive.
Symptoms: Hesitation at low rpm, camshaft position sensor fault code, rough idle, engine warning with power reduction
Direct injection on the M256 inline-six causes carbon deposits on intake valves. Walnut blasting every 60,000–80,000 km recommended.
Symptoms: Hesitation in the lower rev range, rough idle, sporadic misfires on cold start
Rattling on cold start from the wastegate guide bush with design-inherent play. BorgWarner states this is necessary so the wastegate does not stick at operating temperature. Mercedes classes it as state of the art — not a defect.
Symptoms: Rattling or clattering in the first seconds after cold start, disappears after warm-up
Vehicle Weaknesses 7
In CLE C236 model year 2024 (production April to December 2023), an MBUX software bug could permanently deactivate the parking assist emergency braking function. An OTA update fixes the issue.
CLE C236 (2023–2024) was part of a comprehensive Mercedes recall due to potentially defective 80-ampere main fuses that could blow prematurely. Total failure of electrical systems possible.
The 48V electrical system in the CLE C236 shows isolated issues with poorly torqued ground points. Loose 12V/48V ground connections lead to intermittent starting problems.
Early CLE C236 owners report complete MBUX crashes with multiple restarts, HUD failures and a frozen main screen. New vehicles are often delivered with outdated software.
The 9-speed automatic gearbox in the CLE C236 exhibits harsh and jerky shifts in certain driving situations. Outdated transmission software is a common cause; a firmware update resolves it.
Early CLE C236 units show software errors with display failures and problems with driver assistance systems. Vehicles are sometimes delivered with outdated software.
Seatbelt buckles in the CLE C236 rattle while driving. Typical quality issue on early production units. Damping can be retrofitted.