The pulley fitted to the front of the crankshaft is also a vibration damper: a rubber insert connects the outer ring to the inner one. The rubber ages and hardens, in the end it separates, and then the outer ring slips. The rubber ring can also fall out into the engine bay. This is one of the known faults of these engines, mainly on the early production units. The first sign is unusual vibration at idle, then a wobbling, clacking noise from the engine bay. If the pulley slips, it takes the belt drive with it and can touch the oil pan and the front cover. Those then have to be replaced as well, and the material cost alone is around 750 euro. Prevention is simple: it is worth checking the part number of the pulley and replacing an old-specification one before it comes apart while driving. The fault comes up above 170,000 km, but on the early units sooner as well.

In the Mercedes 7 speed 722.9 automatic (7G-Tronic / 7G-Tronic Plus) the mechatronics unit and the conductor plate (Leiterplatte) age over time: jerking on shifts, delayed engagement, a "Getriebe schützen" message, and fault codes on the gearbox electronics.

The Mercedes 5 speed 722.6 automatic (5G-Tronic / NAG1) has three faults that also recur on the used market: (1) the control electronics sit inside the gearbox housing, and a leaking connector lets oil onto the electronics; (2) cooling faults around 2003 (and later) can let antifreeze into the ATF, which shortens its life; (3) wear of the torque converter lock-up clutch contaminates the valve body and causes jerky shifts.

The gasket of the cam cover and the cover seals towards the oil filter housing age, harden and start to seep. On the M112 the oil loss around the cam cover gasket is a big theme in itself. The oil runs down the side and the front of the engine. The visible sign is an oil patch on the floor and an oily engine bay. The leak starts slowly, but the running oil can also get onto the belt drive and the exhaust. The part is not expensive: each of the two cam cover gaskets was around 18 euro. A lot depends on the quality of the repair. The covers of the crankcase breather on the cam cover are held by aluminium screws, and those break easily if someone leans on them: they may only be tightened gently by hand. The fault comes up above 130,000 km.