When Mercedes-Benz first started producing their E Class executive car back in the 1950s, the E stood for Einspritsmotor, the German term for fuel injection engine. Now that this is a common feature in all cars, MB just calls it the E Class. The 9th generation, available since 2010, is a worthy continuation of this line. Some owners report occasional transmission slipping.
According to owners experiencing this problem, the transmission slippage does not occur all the time, and usually only after the car has been sitting for a long time—such as overnight. What is commonly reported is that the transmission will trip during the first few miles, making itself noticeable with both a sound and a jumping of the RPM needle. After the car warms up, the transmission goes back to normal, and the problem doesn’t show up until the next time the car is left to sit for a long period of time.
The possible solutions to this mystery range from the mundane to the serious, and it is difficult to know what exactly is causing the problem. If the car has many miles on it, it is possible that there is some grime clogging up the transmission valves, and a simple flushing of the lines should clear the issue right up. Or it might be that the vehicle is due for a software update, which will recalibrate the various systems to function optimally. Another possibility is simply that the transmission fluid needs to be refilled, low fluid making any shifting slightly harsher than it should otherwise.
If there is anything serious happening with the transmission, allowing the problem to go unchecked could result in a seizing up of the whole system, putting you in a potentially life-threatening situation and leaving you with a horrendously expensive mess on your hands. We highly recommend taking your W212 to a specialized Mercedes Benz service expert for a complete going over and, if needed, repair.
Search for a local, independent Mercedes-Benz repair shop with Mercedes-Benz mechanics that have dealer-level expertise at a fraction of the expense.