Mercedes-Benz OM642 Engine Specs

The Mercedes-Benz OM642 is a turbocharged inline-six common-rail diesel engine produced from 2005 to 2018, one of Mercedes-Benz's most important modern diesel engines, used across the C-Class, E-Class, ML-Class, GL-Class, and the Sprinter van. It represented a significant technological leap over Mercedes' earlier diesel engines, combining a genuinely refined six-cylinder layout with modern common-rail direct injection and turbocharging to deliver both strong performance and impressive fuel economy.

Producing between 204 and 258hp and substantial torque of 500-620Nm, the OM642 uses a DOHC 24-valve head, common-rail direct injection, a turbocharger (with variable-geometry turbochargers on higher-output versions), and a compression ratio of 15.5:1, resulting in genuinely strong pulling power and smooth six-cylinder refinement that made OM642-powered Mercedes models popular among buyers wanting both diesel efficiency and genuine driving refinement. Mercedes rated the OM642 for an impressive 400,000km-plus service life, in keeping with the brand's diesel engineering heritage established by earlier engines like the OM617.

As with any modern common-rail diesel, several maintenance items are worth understanding on used examples. The timing chain, used throughout the OM642 family, should be inspected for stretch and tensioner wear on higher-mileage examples, as chain-related issues have been documented on some early production units. Fuel injectors are sensitive to fuel quality and benefit from periodic cleaning, particularly on higher-mileage examples. The EGR valve is prone to carbon buildup, especially in stop-start urban driving, and periodic cleaning helps maintain smooth running and emissions compliance. The diesel particulate filter, fitted to later, more emissions-compliant versions, requires periodic regeneration cycles best supported by occasional longer highway drives rather than exclusively short trips. Given the OM642's widespread use across Mercedes passenger cars and the Sprinter commercial van, parts availability and mechanic familiarity remain excellent across most markets.