The Mercedes — Benz M271.951 is a 1,796 cc, inline — four petrol engine produced between 2008 and 2015. It features a dual overhead camshaft (DOHC) valvetrain with variable valve timing (VVT) on both intake and exhaust camshafts and multi — point fuel injection (MPFI). In tuned form, it delivers 135 kW (184 PS) and 270 Nm of torque, offering enhanced responsiveness for compact executive applications.
Fitted to models such as the W204 C — Class, W212 E — Class, and R172 SLK, the M…
Production years 2008–2015 meet Euro 5 emissions standards (VCA UK Type Approval #VCA/EMS/5679).
The Mercedes-Benz M271.951 is a 1,796 cc inline-four petrol engine engineered for compact and mid-size platforms (2008–2015). It combines multi-point fuel injection with dual variable valve timing to deliver responsive performance and improved fuel efficiency. Designed to meet Euro 5 standards, it balances sporty driving dynamics with everyday usability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,796 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 82.0 mm × 85.0 mm | |
Power output | 135 kW (184 PS) @ 5,500 rpm | |
Torque | 270 Nm @ 2,800–4,600 rpm | |
Fuel system | Multi-point fuel injection (MPFI) | |
Emissions standard | Euro 5 | |
Compression ratio | 10.7:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Timing chain (double-row, front-mounted) | |
Oil type | MB 229.5 (SAE 5W-40) | |
Dry weight | 148 kg |
The Mercedes-Benz M271.951 was used across Mercedes-Benz's W204/W212/R172 platforms with longitudinal mounting and no licensed partnerships. This engine received platform-specific adaptations-shortened intake manifolds in the R172 and revised cooling routing in the W212-and from 2011 the updated camshaft adjuster design was implemented across all applications, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The M271.951's primary reliability risk is dual camshaft adjuster wear on early builds, with elevated incidence in short-trip urban use. Internal Daimler quality reports from 2012 indicated a significant share of pre-2011 engines requiring adjuster replacement before 150,000 km, while UK DVSA records link a notable portion of emissions-related MOT failures to lambda sensor degradation in high-mileage units. Cold-start cycles and extended idling increase adjuster and chain stress, making oil quality and interval adherence critical.
Analysis derived from Daimler technical bulletins (2008-2015) and UK DVSA failure statistics (2016-2022). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M271.951 offers responsive performance and good refinement, but early models (2008-2010) had reliability concerns, particularly dual camshaft adjuster failures. Later revisions (post-2011) improved adjuster durability, so well-maintained examples can be quite robust. Regular servicing and using high-quality oil (5W-40 MB 229.5) greatly aid longevity.
The biggest issues are dual camshaft adjuster wear (leading to startup rattle or VVT faults), intake carbon buildup affecting throttle response, and lambda sensor degradation causing poor fuel economy. Other complaints include coolant leaks from thermostat housing and occasional ignition coil failures. These are well-documented in Daimler service bulletins.
This 1.8L petrol engine was used across several Mercedes-Benz platforms. It appeared in the C-Class (W204), E-Class (W212), and SLK (R172) as the C 200 Kompressor, E 200 Kompressor, and SLK 200 Kompressor. Smart also used a transverse-adapted version in the Fortwo (W454) from 2011-2015.
Yes, but with limitations. The naturally aspirated M271.951 has modest tuning potential. ECU remaps can yield +10-15 kW safely, primarily improving throttle response. Aftermarket exhaust and intake upgrades offer minor gains. Due to the engine's design, significant power increases require forced induction conversion, which is complex and not OEM-supported.
Moderate. In a C 250 (W204) from around 2010, typical consumption is ~9.8 L/100km (city) and ~6.5 L/100km (highway), or about 29 mpg UK combined. Real-world figures depend on driving style, but expect 28-33 mpg (UK) on mixed roads for a healthy M271.951. Premium fuel (RON 98) is recommended for optimal efficiency.
Yes. The M271 series is an interference engine. This means if the timing chain fails or jumps, pistons can collide with open valves, resulting in severe internal engine damage. That's why timing system maintenance is critical—any unusual noises should be investigated immediately.
Mercedes-Benz specifies a 5W-40 synthetic oil meeting MB 229.5 specification. Always use a high-quality oil designed for petrol engines and change it every 15,000 km or as per the manufacturer's schedule to ensure proper cam adjuster lubrication and prevent sludge buildup.
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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