KNOWN FAULTS · Mercedes-Benz

Mercedes-Benz Clase C (W204) C 200 / 220 CDI (OM646, hasta 2009) common problems.

2007–2014 · Diesel

Sources are not verified in real time and no entry confirms that your car is affected.

2 known faults with sources

Applies if: Only if fitted with 7G-Tronic. Confirm the gearbox type.

7G-Tronic conductor plateGearbox

Engine / equipment: 7G-Tronic automatic gearbox (722.9) in the C, E, S-Class, ML, GL, SLK, Sprinter…
Period mentioned: 2004 onwards (more failures in 2004–2008)
Symptoms: Gearbox stuck in 2nd or 3rd (limp mode), harsh shifts, delay engaging D or R, gearbox warning often without an engine light; turning off and restarting clears it for a while.
Possible cause described: The conductor plate (the control unit with built-in speed sensors) fails from heat and vibration. Oil leaks through the 13-pin connector are also common.
Check for the garage: Diagnose with Xentry/STAR to see the sub-codes (a basic reader only shows P0700). Check for oil in the gearbox connector.
Cost cited in the source: Approx. €1,400–2,800 (estimate)A rough figure from the original database, not an up-to-date quote.

OM646 injector seals (black death)Injection / intake

Engine / equipment: OM646 2.1/2.2 CDI (C 200/220 CDI W203 and W204, E 200/220 CDI W211, Vito, Sprinter) and the 2.2 CRD in the Chrysler PT Cruiser
Period mentioned: 2002–2010
Symptoms: Puffing or “chuffing” at idle, a diesel smell under the engine cover and a hard black crust around the injectors; power loss from sooted intake flaps or turbo.
Possible cause described: The copper washer under each injector fails and combustion gases escape, carrying diesel and oil that harden into a black crust (“black death”). Soot also seizes the intake flaps and turbo mechanism. Otherwise it is a very robust engine.
Check for the garage: Remove the engine cover and look for black residue around the injectors, listen at idle and check the intake flaps.
Cost cited in the source: Injector washers: approx. €200–800 depending on how advanced the crust isA rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: from 150,000 km. This is not a maintenance interval and does not predict a failure.