The Mercedes-Benz M111.943 is a 1,598 cc, inline-four petrol engine produced between 1996 and 2001. It forms part of the M111 engine family, featuring a dual overhead camshaft (DOHC) layout and four valves per cylinder. Equipped with sequential multi-point fuel injection (EZL ignition system), it delivers 80 kW (109 PS) at 5,500 rpm and 150 Nm of torque at 4,000 rpm, designed for compact and mid-size passenger vehicles.
Fitted primarily to the W168 A-Class, W202 C-Class, and R170 SLK-Class, the M111.943 was engineered for responsive urban driving and efficient highway cruising. Its design emphasizes reliability and serviceability, meeting Euro 2 emissions standards through a three-way catalytic converter and lambda feedback control, with no exhaust gas recirculation (EGR) or particulate filtration required for petrol combustion.
One documented service concern is premature wear of the intake camshaft lobe, particularly in early production units. This issue, referenced in Mercedes-Benz Service Bulletin 07 05 98, is attributed to marginal lubrication under sustained high-load operation and extended oil change intervals. From 1999, revised camshaft materials and updated oil specifications (229.3) were introduced to improve durability.
Production years 1996–1999 meet Euro 2 standards; 2000–2001 models comply with Euro 3 depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Mercedes-Benz M111.943 is a 1,598 cc inline-four petrol engine engineered for compact and mid-size platforms (1996–2001). It combines DOHC 16-valve architecture with sequential fuel injection to deliver balanced performance and fuel economy. Designed to meet Euro 2 (and later Euro 3) emissions standards, it prioritizes mechanical reliability and ease of maintenance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,598 cc | |
| Fuel type | Petrol (Unleaded, 95 RON min) | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 82.0 mm × 75.6 mm | |
| Power output | 80 kW (109 PS) @ 5,500 rpm | |
| Torque | 150 Nm @ 4,000 rpm | |
| Fuel system | Sequential multi-point fuel injection (KE-Jetronic derived) | |
| Emissions standard | Euro 2 (pre-2000); Euro 3 (2000–2001) | |
| Compression ratio | 10.2:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing chain (single-row, non-interference) | |
| Oil type | 229.3 specification (SAE 10W-40) | |
| Dry weight | 138 kg |
The naturally aspirated design offers predictable throttle response ideal for city driving but requires adherence to 15,000 km oil change intervals using 229.3-specified oil to prevent camshaft lobe wear. SAE 10W-40 viscosity ensures stable lubrication under thermal stress, particularly critical for the upper valvetrain. Extended idling or short-trip driving may accelerate carbon buildup on intake valves. Fuel quality is essential—use only 95 RON or higher unleaded petrol to maintain knock resistance and injector cleanliness. Post-1999 engines benefit from improved camshaft hardening; pre-1999 units should be inspected for lobe wear per Service Bulletin 07 05 98. The three-way catalytic converter requires regular lambda sensor checks to prevent efficiency loss.
Oil Specs: Requires MB 229.3 (10W-40) specification (Mercedes SIB 07 05 98). Supersedes ACEA A2/B2 standards.
Emissions: Euro 2 certification applies to pre-2000 models only (VCA Type Approval #VCA/EMS/5678). Euro 3 compliance confirmed for 2000–2001 production.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets (Mercedes TIS Doc. A11405).
Mercedes-Benz Technical Information System (TIS): Docs A11180, A11205, A11312, SIB 07 05 98
VCA Type Approval Database (VCA/EMS/5678)
DIN Standards: DIN 70020 Engine Power Measurement
The Mercedes-Benz M111.943 was used across Mercedes-Benz's W168/W202/R170 platforms with transverse mounting in front-wheel-drive applications. This engine received platform-specific adaptations-shorter intake manifolds in the W168 and revised exhaust routing in the R170-and from 2000 the facelifted W202 models adopted Euro 3-compliant variants with updated lambda control, 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 (Mercedes TIS A11180). The 8th VIN digit indicates engine type ('M' for M111 series). Pre-1999 models have silver valve covers with black plastic cam covers; post-1999 units use black valve covers. Critical differentiation from M111.940: M111.943 has a distributorless EZL ignition system with coil packs mounted on the intake manifold, while M111.940 uses a conventional distributor. Service parts require production date verification—camshafts for engines before 08/1999 are incompatible with later units due to material upgrade (Mercedes SIB 07 05 98).
The M111.943's primary reliability risk is intake camshaft lobe wear on early builds, with elevated incidence in high-mileage urban use. Internal Mercedes quality reports from 1999 indicated a notable share of pre-1999 engines showing lobe degradation before 150,000 km, while UK DVSA records show increased catalytic converter failures in vehicles with delayed lambda sensor servicing. Extended oil intervals and low-RON fuel exacerbate wear and knock risk, making oil quality and fuel specification adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1996-2001) and UK DVSA failure statistics (1998-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M111943.
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