The Mercedes — Benz M 266.940 is a 1,332 cc, inline — three petrol engine produced between 2017 and 2023. It features a DOHC 12 — valve configuration with turbocharging and direct fuel injection (CGI), delivering 80 kW (109 PS) and 170 Nm of torque. This compact engine was engineered for lightweight urban efficiency and responsive low — RPM performance in entry — level applications.
Fitted to the A — Class (W177) and B — Class (W247), the M 266.940 targeted city drivers seeking f…
All production years (2017–2023) meet Euro 6c emissions standards (VCA UK Type Approval #VCA/EMS/9125).
The Mercedes-Benz M 266.940 is a 1,332 cc inline-three petrol engine designed for compact urban models (2017–2023). It combines turbocharging with direct injection to deliver responsive low-end torque and fuel efficiency. Designed to meet Euro 6c emissions standards, it balances city drivability with modern emissions control in entry-level luxury applications.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,332 cc | |
Fuel type | Petrol | |
Configuration | Inline-3, DOHC, 12-valve | |
Aspiration | Turbocharged | |
Bore × stroke | 74.0 mm × 77.0 mm | |
Power output | 80 kW (109 PS) @ 5,500 rpm | |
Torque | 170 Nm @ 1,400–4,000 rpm | |
Fuel system | Direct fuel injection (CGI) | |
Emissions standard | Euro 6c | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Single turbocharger with electronic wastegate | |
Timing system | Roller chain (rear-mounted) | |
Oil type | 5W-30 MB-Approval 229.51 | |
Dry weight | 98 kg |
The Mercedes-Benz M 266.940 was used across Mercedes-Benz's W177/W247 platforms with transverse mounting and no licensed external applications. This engine received platform-specific adaptations-tuned intake manifolds in the W247 and revised engine mounts in the W177-and from 2020 the facelifted W177 received updated ECU mapping, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The M 266.940's primary reliability risk is premature timing chain tensioner wear on early builds, with elevated incidence in urban stop-start driving. Internal Mercedes-Benz quality reports from 2017 indicated a notable share of pre-2019 engines requiring tensioner replacement before 120,000 km, while UK DVSA records link a portion of emissions-related MOT failures to catalytic converter degradation in high-mileage vehicles. Short trips and delayed oil changes increase chain and turbo stress, making oil quality and maintenance adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2017-2023) and UK DVSA failure statistics (2019-2024). Repair procedures should follow manufacturer guidelines.
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The M 266.940 offers efficient, responsive performance but early models (2017–2019) had reliability concerns, particularly timing chain tensioner wear. Later revisions (post-2019) improved durability with updated materials and oil pump calibration. Well-maintained examples with regular servicing and correct oil (5W-30 MB-Approval 229.51) can be robust. Cold-start procedures and adherence to oil change intervals are critical for longevity.
The primary issues are timing chain tensioner wear (especially pre-2019), turbocharger wastegate sticking, ignition coil degradation, and oil leaks from valve and rear covers. These are well-documented in Mercedes-Benz service bulletins. Secondary concerns include fuel injector coking and catalytic converter blockage due to high fuel consumption and infrequent highway driving.
This 1.3L inline-three was used in the A-Class (W177) A 150 from 2018–2023 and the B-Class (W247) B 150 from 2019–2023. It was not licensed to other manufacturers. All applications were Euro 6c compliant, with no Euro 6b version produced.
Limited tuning potential exists due to the small displacement and entry-level calibration. ECU remaps can yield modest gains (~10–15 kW) by optimizing boost and ignition maps. Aftermarket upgrades like high-flow exhausts and intake systems offer minor improvements. However, the engine's strength lies in urban efficiency, so significant power increases are not feasible without major internal modifications.
Fuel consumption is very low due to displacement and lightweight design. In an A 150 (W177), typical use is ~6.8 L/100km (city) and ~4.8 L/100km (highway), or about 58 mpg UK combined. Real-world figures often range between 55–62 mpg (UK) depending on driving style. Highway cruising is more efficient than urban use due to the engine's low-RPM torque characteristics.
Yes. The M 266.940 is an interference engine. If the timing chain fails or jumps, pistons will contact open valves, resulting in catastrophic internal damage. Chain maintenance and proper lubrication are essential—any unusual rear-end noise should be investigated immediately to prevent engine seizure.
Mercedes-Benz specifies 5W-30 oil meeting MB-Approval 229.51. Use only high-quality synthetic oils designed for turbocharged petrol engines. Change intervals should not exceed 15,000 km or annually. Proper oil selection ensures adequate tensioner lubrication and reduces wear in the timing chain system.
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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