Mercedes-Benz CDI (badge, not an engine)

turbocharged · diesel · 1997–present

Also known as: cdi, mercedes cdi, bluetec cdi, cdi diesel

CDI is a badge, not an engine — Mercedes-Benz's word for a common-rail diesel, on Mercedes and Smart in this catalogue, from a 0.8 three-cylinder to a 4.0 V8.

⚑ The number on the boot is not the displacement. A 220 CDI is 2.1 or 2.2 litres; a 320 CDI is 3.0. Mercedes' badge numbers mark where a car sits in the range, not how big its engine is, so searching a part catalogue by the badge number finds nothing and the litre figure a listing prints may be either.

⚑ The same badge at the same size can be two different engines. The W203 C-Class was sold as a 2.1 CDI with the OM611 and later with the OM646 — different families, same badge, same displacement, same model. Only the year and the OM code separate them.

What the badge covers here:

Four-cylinder — OM611, OM646, OM651, OM654, in that order over 25 years, plus OM640 in the A- and B-Class and OM668 before it.
Five and six in line — OM612, OM613, OM648.
V6 — OM642, the 3.0 in almost everything from the W211 onward.
V8 — OM629, the 4.0.
Three-cylinder — OM660 and OM639, the Smart diesels.

⚑ Not every CDI is a Mercedes engine. The Vito W447's 1.6 CDI is Renault-derived and drives the front wheels — the alliance running the other way from the K9K, which Mercedes sells as the OM607/OM608. A Mercedes badge is not a guarantee of Mercedes parts, and the service literature for that engine is Renault's.

Establish the OM code. It is on the engine and in the data card, and every family above has its own page here.

Cars fitted with this engine

24 generations, across 2 makes. From the authored catalogue — an absent car means the catalogue has not reached it, not that the engine was never fitted.

Mercedes-Benz

Smart

Information, not instruction

CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.

Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

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