Mercedes-Benz OM 934 engine: displacement, ratings and generations

The Mercedes-Benz OM 934 is a 5.1-litre in-line four-cylinder diesel engine from Daimler Truck, built for medium-duty trucks and listed by Mercedes-Benz Powertrain for buses as well. It is the four-cylinder member of the medium-duty 93X model series. Daimler presented it in March 2012 with Euro VI for every rating, and in 2013 it went into the Euro VI generation of the Mercedes-Benz Atego. Mercedes-Benz Powertrain lists ratings from 115 kW to 170 kW. On this site it is one of the engines of the Mercedes-Benz Atego.

Status as of 26 October 2026. Read that day: the Truck Euro VI engine page of Mercedes-Benz Powertrain, its Truck Euro VI portfolio (dated 09/2025) and its Bus Euro VI portfolio, Daimler’s launch release for the OM 93x engines dated 13 March 2012, and its Atego releases of 7 February 2013, 19 March 2013 and 7 December 2023. All are the maker’s own documents. The 2012 and February 2013 releases were read in their Italian versions and the March 2013 release in French; what they say is given here in English, without quotation marks.

Maker, name and layout

The OM 934 is a Daimler Truck engine. Daimler’s 2012 release says the OM 93x engines are built in the Daimler Trucks engine plant in Mannheim, where the cylinder head, camshafts, crankcase, connecting rods and crankshaft are made as well. Mercedes-Benz Powertrain, which offers engine systems, transmissions and axles as powertrain components, lists the engine in its truck and bus portfolios; Daimler Truck AG publishes both.

The name follows the scheme the truck portfolio sets out: OM marks an oil (diesel) engine, then “93 = 93X model series (MD)”, the medium-duty series, and “4 = L4 cylinder engine (5.1 l)”. The engine page gives the OM 934 as “Arrangement: In-line 4 | Displacement: 5.1 l”. Daimler Truck’s December 2023 release and the index of the bus portfolio also use the longer designation OM 934 LA. The 93x series has two members, the four-cylinder OM 934 and the six-cylinder OM 936 of 7.7 litres; the 2012 release gives both a bore of 110 mm, a stroke of 135 mm and a cylinder spacing of 128 mm.

For the medium-duty series, Mercedes-Benz Powertrain lists diesel engines in an in-line arrangement with cooled exhaust gas recirculation, a “Common rail injection system up to 2400 bars and multiple injection”, a “Tailor-made charging system with 1- and 2-stage turbochargers”, two overhead camshafts with 4-valve technology and a “One box” exhaust after-treatment with SCR and DPF. Daimler’s 2012 release adds the detail behind those lines:

• Cylinder head and valve gear. A crossflow cylinder head with four valves per cylinder and two overhead camshafts. The exhaust camshaft carries a variable camshaft phaser (VCP); when the diesel particulate filter is to be regenerated, the release says, the valve timing is advanced by up to 65 degrees so that the exhaust gas leaves the cylinder hotter.
• Injection and combustion. Common-rail injection with up to five individual injections per cycle, a peak firing pressure above 200 bar and an injection pressure of up to 2,400 bar.
• Turbocharging. On the OM 934, a single-stage exhaust-gas turbocharger up to 130 kW and, on the higher ratings, two-stage charging with two turbochargers; every charging system has an electronically controlled wastegate.
• Engine brake. A decompression engine brake, operated in two stages on the OM 934 from the steering-column lever, with a braking power of 145 kW and 170 kW for the four-cylinder engines; the release gives the maximum braking power as reached at 2,700–3,000 rpm. Mercedes-Benz Powertrain gives engine brakes of up to 300 kW brake power for the medium-duty series as a whole and no separate figure for the OM 934. What an engine brake is, and how the law groups it, is set out in retarders and engine braking.
• Gear train and power take-off. A gear train at the flywheel end drives the camshafts and the auxiliaries and is the base for an optional rear engine power take-off with up to 600 Nm of usable torque.

Mercedes-Benz Powertrain’s engine page gives a weight of 495 kg (DIN 70020 GZ) with the single-stage charger, a length of 982 mm, a width of 934 mm and a height of 976 mm, marking the values as dependent on the equipment installed. The bus portfolio lists 495 kg with the single-stage charger and 510 kg with the dual-stage chargers. The 2012 release gives a dry weight of 495 kg to DIN 70020-A.

Euro VI ratings

Mercedes-Benz Powertrain’s bus portfolio lists four ratings for the OM 934, each with its rated power at 1,800 rpm. The truck portfolio of 09/2025 and the engine page list the first two of them.

Daimler’s 2012 launch release lists the same four power levels for the OM 934, 115 kW (156 CV), 130 kW (177 CV), 155 kW (211 CV) and 170 kW (231 CV), but each at 2,200 rpm, and gives 900 Nm for the 170 kW version; the Italian release writes CV where the English portfolios write hp, with the same figures. The documents do not explain why the rated speed differs between the 2012 release and the current portfolios, and both are given here as the maker wrote them. Daimler’s Atego releases of February and March 2013 give the OM 934 in the Atego as four ratings from 115 kW (156 hp) to 170 kW (231 hp). How kW and hp relate, and what the engine speed beside each figure means, is explained in reading truck power figures.

Generations

The maker documents read for this page describe one OM 934 engine series, introduced in 2012, and do not number OM 934 generations. The “second generation” in Daimler Truck’s 2023 release is the second generation of the Atego truck, not of the engine.

In the 2012 release, Daimler named light, medium and heavy distribution trucks and light and medium construction vehicles among the engines’ fields, gave city and intercity buses as a field of the six-cylinder, and said later stages would bring use in other markets, in other Daimler Trucks models on several continents and as an industrial engine. Its February 2013 Atego release introduced four new four-cylinder OM 934 engines of 5.1 litres for the Atego, all meeting Euro VI; the Belgian release of March 2013 says they power the lighter-tonnage variants of the Atego, which covers distribution trucks of 6.5 t to 16 t gross vehicle weight. In December 2023 Daimler Truck wrote of the OM 934 LA and OM 936 LA engines: “Their most recent versions still power the Atego today.” Neither that release nor the other documents read date or name those later versions.

Fuels and emission class

Mercedes-Benz Powertrain describes its medium-duty engines as “4- and 6-cylinder diesel engines in an in-line arrangement with cooled exhaust gas recirculation”, and none of the documents read for this page lists a gas-fuelled OM 934. They do not mention HVO or other paraffinic diesel for the engine either; what HVO is and the standard it is sold under are set out in what is HVO fuel.

Daimler’s 2012 release says every rating of the OM 93x series meets Euro VI, which, it notes, was to come into force in the EU on 1 January 2014. The documents do not say which Euro VI step the current OM 934 is certified to; the steps and what Euro 7 adds are covered in Euro VI and Euro 7.

For the exhaust after-treatment, the 2012 release lists, in the direction of flow, an oxidation catalyst (DOC), a diesel particulate filter with a precious-metal coating (DPF), an SCR catalyst for nitrogen oxides and a slip catalyst after it, with a single tailpipe on the medium-duty vehicles. AdBlue is dosed into the SCR catalyst without compressed air, and a separate HC doser at the engine’s exhaust outlet supplies the fuel for regenerating the particulate filter. How SCR and AdBlue work is covered in SCR and AdBlue explained.

Trucks and buses on this site with the Mercedes-Benz OM 934

One model page on this site lists the OM 934 among its engines, and no other model page names it, in its engine list or in its notes. Mercedes-Benz Powertrain lists the engine for buses, but no bus on this site records it. The figures below are those recorded on the model’s own page, from that page’s own source; they are not the engine-level table above.