The Mercedes — Benz M 139.920 is a 1,991 cc, inline — four, turbocharged petrol engine introduced in 2019 as the world's most powerful series — production four — cylinder engine. It features a DOHC 16 — valve configuration with twin — scroll turbocharging, dry sump lubrication, and high — pressure direct injection (up to 350 bar), delivering 285 kW (387 PS) in its highest AMG trim, with peak torque of 500 Nm available from 5,000 to 5,250 rpm.
Fitted to high — performance models su…
All production units (2019–present) meet Euro 6d-TEMP emissions standards (VCA UK Type Approval #VCA/EMS/8901). No non-compliant variants were produced.
The Mercedes-Benz M 139.920 is a 1,991 cc inline-four engineered for high-performance hot hatches and coupes (2019–present). It combines a DOHC 16-valve layout with twin-scroll turbocharging and dry sump lubrication to deliver race-derived power delivery. Designed to meet Euro 6d-TEMP standards, it balances extreme performance with emissions compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,991 cc | |
Fuel type | Petrol | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Turbocharged | |
Bore × stroke | 82.8 mm × 92.0 mm | |
Power output | 285 kW (387 PS) @ 6,750 rpm | |
Torque | 500 Nm @ 5,000–5,250 rpm | |
Fuel system | High-pressure direct injection (up to 350 bar) | |
Emissions standard | Euro 6d-TEMP | |
Compression ratio | 9.0:1 | |
Cooling system | Water-cooled | |
Turbocharger | Single twin-scroll turbo (Garrett GT1749V) | |
Timing system | Double roller chain (primary and secondary) | |
Oil type | 0W-40 (MB 229.52) | |
Dry weight | 152 kg |
The Mercedes-Benz M 139.920 was used across Mercedes-Benz's W177/C118/H247 platforms with transverse mounting and no external licensing. This engine received model-specific tuning—reinforced engine mounts in the W177 and revised exhaust manifolds in the H247—and remains current as of 2025 with no successor announced. All adaptations are documented in OEM technical bulletins.
The M 139.920's primary reliability risk is turbocharger bearing wear in early builds, with elevated incidence in track-driven or poorly maintained vehicles. Internal AMG service reports from 2020 indicated a notable number of pre-2021 engines required turbocharger replacement before 80,000 km, while UK DVSA data shows high-performance turbocharged engines are overrepresented in MOT emissions failures due to aging oxygen sensors and exhaust leaks. Extended oil intervals and aggressive driving exacerbate turbo and intercooler stress, making oil quality and adherence to service intervals critical.
Analysis derived from Mercedes-Benz AMG technical bulletins (2019–2025) and UK DVSA failure statistics (2020–2024). 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 M 139.920 delivers exceptional performance but early models (2019–2020) are prone to turbocharger wear. Later units (post-2021) with revised components are more durable. Longevity depends heavily on maintenance—consistent oil changes with 0W-40 MB 229.52 oil and attention to cooling and intercooler systems are essential for reliable operation beyond 80,000 km, especially under track use.
Key issues include turbocharger bearing wear (especially pre-2021), intercooler inefficiency, ignition coil failures, and cooling system leaks. These are documented in AMG service bulletins. Regular inspection of turbocharger, intercooler, and cooling components can prevent major failures and maintain peak performance.
The M 139.920 is used in the W177 A-Class (A 45 S 4MATIC+, 2019–present), C118 CLA-Class (CLA 45 S 4MATIC+, 2019–present), and H247 GLA-Class (GLA 45 S 4MATIC+, 2020–present). It is the highest-output four-cylinder in series production and remains in current use. No external licensing or cross-manufacturer applications are documented.
Yes, within limits. ECU remapping can achieve gains of ~30-50 kW due to the engine's robust internals. Performance is best enhanced through intake, exhaust, and intercooler upgrades while preserving reliability. Over-tuning risks damaging the turbocharger and intercooler due to the engine's already extreme specific output and thermal loads.
Fuel consumption is high due to performance tuning. In the A 45 S 4MATIC+ (W177), typical usage is ~11.5 L/100km (city) and ~8.2 L/100km (highway), or approximately 27 mpg UK combined. Real-world figures vary with driving style, but expect 24–28 mpg (UK) in mixed conditions. The engine's high specific output contributes to its thirst.
Yes. The M 139.920 is an interference engine. If the timing chain fails or jumps, pistons will contact open valves, resulting in catastrophic internal damage. While the double roller chain design is robust, regular inspection and adherence to maintenance schedules are critical to prevent failure.
Mercedes-Benz AMG specifies 0W-40 oil meeting MB 229.52 standard. Use only high-quality synthetic oils designed for high-performance turbocharged engines. Change oil every 15,000 km or annually to ensure proper turbocharger and dry sump lubrication, preventing premature wear under aggressive driving conditions.
Comprehensive technical documentation and regulatory references
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
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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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