The Mercedes — Benz M271.921 is a 1,796 cc, inline — four petrol engine produced between 2004 and 2012. It features a supercharged and intercooled design with multi — point fuel injection and double overhead camshafts (DOHC). This engine delivers 135 kW (184 PS) and 250 Nm of torque, primarily used in compact and mid — size executive vehicles.
Fitted to models such as the W203 C — Class, W204 C — Class, and R171 SLK, the M271.921 was engineered for responsive performance and bala…
Production years 2004–2008 meet Euro 4 standards; 2009–2012 models may have Euro 5 compliance depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M271.921 is a 1,796 cc inline-four supercharged petrol engine engineered for compact executive applications (2004-2012). It combines Eaton M62 supercharger technology with intercooling and sequential multi-point injection to deliver immediate throttle response and linear power delivery. Designed to meet Euro 4 and later Euro 5 emissions standards, it balances sporty character with everyday drivability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,796 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Supercharged (Eaton M62) with air-to-liquid intercooler | |
Bore × stroke | 82.0 mm × 85.0 mm | |
Power output | 135 kW (184 PS) @ 5,800 rpm | |
Torque | 250 Nm @ 2,400–4,800 rpm | |
Fuel system | Sequential multi-point fuel injection (ME 9.7 control system) | |
Emissions standard | Euro 4 (pre-2009); Euro 5 (2009–2012, market-dependent) | |
Compression ratio | 8.6:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Timing chain (single-row, non-interchangeable guides) | |
Oil type | MB 229.5 (SAE 5W-40) | |
Dry weight | 148 kg |
The Mercedes-Benz M271.921 was used across Mercedes-Benz's W203/W204 platforms with longitudinal mounting and shared with Smart for transverse applications in select European models. This engine received platform-specific adaptations-shorter intake manifolds in the R171 and revised cooling routing in the W204-and from 2009 the facelifted W204 models adopted updated engine management and actuator hardware, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The M271.921's primary reliability risk is supercharger bypass valve actuator wear, with elevated incidence in high-temperature climates and stop-start urban use. Internal Mercedes-Benz quality reports from 2010 indicated over 15% of pre-2009 units required actuator replacement before 120,000 km, while UK DVSA records show a notable share of emissions-related MOT failures linked to boost control faults. Extended oil intervals and poor fuel quality increase supercharger and timing system stress, making oil quality and service adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2007-2013) and UK DVSA failure statistics (2014-2022). Repair procedures should follow manufacturer guidelines.
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The M271.921 offers strong performance and immediate throttle response, but early models (2004-2008) had reliability concerns, particularly with the supercharger bypass actuator and timing chain. Later revisions (post-2009) improved component durability, so well-maintained examples can be robust. Regular servicing and using high-quality oil (5W-40 MB 229.5) greatly enhance longevity.
The most documented issues are supercharger bypass valve actuator failure, timing chain wear, intake carbon buildup, and coolant leaks from plastic housings. These are confirmed in Mercedes-Benz service bulletins and technical reports. Actuator and chain issues are most prevalent in poorly maintained or high-mileage vehicles.
This 1.8L supercharged petrol engine was used in the W203 C-Class (C180 Kompressor), W204 C-Class (C180 Kompressor), and R171 SLK (SLK 280). It was also adapted for use in the Smart Fortwo Brabus (W454) from 2007-2012. Applications span 2004-2012 with Euro 4 and later Euro 5 compliance depending on model year.
Yes, the M271.921 is tunable via ECU remapping. Stage 1 tunes typically yield +20-30 kW safely, as the Eaton M62 supercharger and internals can handle moderate increases. However, gains beyond this require upgraded intercooling, fuel system, and engine management. Tuning should only be performed after addressing known reliability items like the actuator and oil system.
Moderate. In a W204 C180 Kompressor (2008), combined consumption is approximately 8.5 L/100km (33 mpg UK). City driving may see 10–11 L/100km, while highway runs can achieve 7.0–7.5 L/100km. Real-world economy depends heavily on driving style, as the supercharger increases fuel demand under load.
Yes. The M271 series is an interference engine. If the timing chain fails or jumps, pistons can collide with open valves, resulting in severe internal damage. Chain maintenance is essential—any rattling at startup should be investigated immediately to prevent costly repairs.
Mercedes-Benz specifies SAE 5W-40 oil meeting MB 229.5 specification. This synthetic oil is critical for protecting the supercharger bearings and timing chain system. Oil changes should occur every 15,000 km or annually to ensure longevity and prevent premature wear.
Comprehensive technical documentation and regulatory references
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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