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 M271.951 was engineered for dynamic driving characteristics with improved throttle response and mid-range pull. Emissions compliance was achieved through a close-coupled three-way catalytic converter and lambda control, allowing Euro 5 compliance across its production run.
One documented concern is premature camshaft adjuster wear, particularly in early builds subjected to extended oil change intervals. This issue, referenced in Daimler Service Information Bulletin 271.951-01-08-02, stems from delayed oil pressure delivery to the dual VVT adjusters during cold starts. From 2011, revised camshaft adjusters with improved sealing and oil channels were introduced to mitigate failure risk.
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 naturally aspirated design provides linear power delivery ideal for responsive driving but demands strict adherence to 15,000 km oil service intervals to prevent dual camshaft adjuster wear and timing chain degradation. MB 229.5 (5W-40) oil is essential due to its specific viscosity and additive package protecting the variable valve timing system. Cold-start idling should be minimized to ensure prompt oil pressure build-up at the cam adjusters. The MPFI system is robust but sensitive to low-quality fuel, requiring regular use of premium unleaded (RON 98) to maintain valve cleanliness. Post-2011 models feature updated cam adjusters; pre-2011 units should be inspected per Daimler SIB 271.951-01-08-02. Catalytic converter longevity depends on proper lambda sensor function and avoidance of oil burning.
Oil Specs: Requires MB 229.5 specification (Daimler SIB 271.951-01-08-02). Compatible with ACEA A3/B4.
Emissions: Euro 5 certification applies to all production years (VCA Type Approval #VCA/EMS/5679).
Power Ratings: Measured under DIN 70020 standards. Output assumes RON 98 fuel and factory ECU calibration (Daimler TIS Doc. A34010).
Daimler Technical Information System (TIS): Docs A32870, A33122, SIB 271.951-01-08-02
VCA Type Approval Database (VCA/EMS/5679)
ISO 1585: Road vehicles — Engine test code — Net power
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.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block near the exhaust manifold (Daimler TIS A33015). The 8th VIN digit indicates engine family ('1' for M271 series). Pre-2011 models have silver cam covers with black intake manifolds; post-2011 units use black cam covers. Critical differentiation from M271.910: Original M271.951 uses Bosch ME 7.10 ECU with 120-pin connector, while M271.910 uses ME 2.8 with 80-pin. Service parts require production date verification - cam adjusters before 09/2011 are incompatible with later units due to internal redesign (Daimler SIB 271.951-01-08-02).
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.
Find answers to most commonly asked questions about MERCEDES-BENZ M271951.
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Regulation (EC) No 715/2007
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