Known faults for the Mercedes-Benz Clase S (W222).

Engine / equipment

OM642 3.0 V6 CDI/BlueTEC (280/300/320/350 CDI, ML, GL, R, Sprinter)

Period mentioned

2005 onwards

Symptoms

Oil pooling in the engine's V, burning oil smell, drips under the engine; or a hiss or chirp next to an injector with an exhaust smell.

Possible cause described

The oil cooler seals (in the engine's V) degrade. Separately, injector washers leak combustion gas and carbon builds up around the injector.

Check for the garage

Visual inspection of the engine's V and the base of the injectors.

Cost cited in the source

Oil cooler seals: labour-heavy, approx. €800–1,800 (estimate)A rough figure from the original database, not an up-to-date quote.

Sources from the original database

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.

Sources from the original database

Engine / equipment

OM654 2.0 and OM656 3.0 diesel (C, E, S, GLC, GLE, GLS, G-Class from 2016)

Period mentioned

2016–2026

Symptoms

AdBlue or emissions warnings with a start countdown; particulate filter warning; power loss or rough idle from a dirty EGR.

Possible cause described

These are robust engines; faults concentrate in the emissions system. The AdBlue system (injector, NOx sensors and SCR catalyst) sometimes fails, especially in the cold, and the particulate filter and EGR foul if the car mostly does short trips.

Check for the garage

Read AdBlue and NOx sensor codes with Xentry, check the particulate filter regeneration history and how the car is used (short trips).

Cost cited in the source

AdBlue system: approx. €500–1,200; particulate filter: €1,000–2,000A rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: from 100,000 km. This is not a maintenance interval and does not predict a failure.

Sources from the original database

Engine / equipment

9G-Tronic automatic gearbox (725.0 and 725.1): C-Class W205 and W206, E W212 and W213, CLS, S W222 and W223, GLC, GLE, GLS, SL and SLC

Period mentioned

2013–2026

Symptoms

Harsh or jerky shifts (especially 1st to 2nd and when cold), vibration, delayed shifts or limp mode; sometimes the gear will not engage from N to D. Codes P073E00 and P07B700.

Possible cause described

Mercedes acknowledges in a technical bulletin complaints of harsh shifts, shudder and limp mode with various causes. In the early years (2014–2016) it is usually software or adaptation rather than mechanical damage; in other cases the pressure sensor built into the gearbox control unit fails.

Check for the garage

Follow the Mercedes bulletin: reproduce the complaint, save the EEPROM, check the oil level, run the Xentry valve flush, update engine, gearbox and shift unit software and perform the standstill adaptation. If it persists, check the control unit.

Cost cited in the source

Software update and adaptation: the most common and cheapest fix; repairing or replacing the control unit costs considerably more (the sources give no comparable figures)A rough figure from the original database, not an up-to-date quote.

Sources from the original database

Engine / equipment

AIRMATIC air suspension: E-Class W211, W212 and W213, S W220 to W223, CLS, CL, ML W164, GL, GLE and GLS

Period mentioned

2002–2026

Symptoms

One corner sags overnight, suspension fault warning, the compressor runs a lot or a compressor overheated message appears; eventually the car sits low and rides hard.

Possible cause described

The air bellows on the struts leak with age, often at the upper crimp rings, and the compressor overworks until it burns out. The valve block and lines also leak, and the compressor relay (in the rear SAM on W221, W222 and W213) and ride height sensors fail.

Check for the garage

Spray soapy water on bellows, lines and valve block; read each corner's data with Xentry; check the compressor fuse and relay. Do not replace the compressor without fixing the leak first, or the new one will fail soon.

Cost cited in the source

Compressor: approx. €600–1,200 at an independent garage (converted from Canadian dollars); bellows: depends on the cornerA rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: 95,000–115,000 km. This is not a maintenance interval and does not predict a failure.

Sources from the original database