2012 Mercedes-Benz C-Class Pricing and Specs

If the transmission is working properly between bouts of slippage, then it’s reasonable to think that this could be an electronic problem rather than a mechanical one. By turning the ignition off and then restarting, you’re effectively resetting the computer that controls the transmission. That’s why the gearbox comes good for a period before reverting to its old tricks.

That’s on the surface, anyway, but the problem could also be within the torque converter or something intermittent inside the actual gearsets, clutches, bands or valve body that is giving the same set of symptoms.

Ultimately, this is probably going to require a trip to a transmission specialist who will be able to identify the cause more accurately. In the meantime, though, there’s something you can try that might reset the transmission more permanently. On this model Mercedes-Benz, there’s a specific transmission-reset procedure that should take the gearbox back to its original factory settings. If that’s the case, it might fix your problem, but if not, then you need to call in the experts.

The procedure starts with getting in the car, closing all the doors and turning the ignition key to the on position, but not actually starting the engine. You should have all the dashboard lights illuminated at this point. Then, press the accelerator pedal right to the floor, making sure you can feel that the kick-down détente has been activated. Hold the pedal all the way down for at least 60 seconds and then, without releasing the accelerator, turn off the ignition. Don’t open the door and don’t remove the key from the ignition. Now release the accelerator and wait five minutes before starting the engine and going for a test drive.

Good luck.

Colleagues of mine have noted that the C43 isn’t at its happiest when taking off from a standing start sometimes, particularly if the stop-start function is engaged. That said, the harshest description of the problem was the odd clunk when launching the car, but even with that system switched off, the AMG sometimes seems to have problems deciding which gear to select, leading to a lack of smoothness. Perhaps it’s not helped by the fact that the car is all-wheel-drive, and grips the road extremely well when perhaps a little `give’ in the driveline mightn’t be a bad thing. Maybe it’s the traction-control stepping in too early and interrupting the flow of power to the wheels.

That said, your problem sounds a lot more severe than that. The C43 uses a conventional torque converter automatic transmission, so it doesn’t suffer some of the jerkiness that other cars using dual-clutch technology can. It’s puzzling though, that the computer isn’t throwing up any fault codes, so maybe your car is simply doing what some C43s do to a greater or lesser extent. If it’s as bad as you say, it’s not good enough and you should pursue the problem with Mercedes-Benz and have the problem corrected under warranty.

I’ll assume you’re talking about a C200, Kevin, which was the most popular Benz model with a 200 in its name back in those days. The good news is that, no, that engine doesn’t need a timing belt change. That’s because it uses a timing chain rather than a rubber timing belt and, all things being equal, the timing chain should last the lifespan of the car itself.

All Mercedes-Benz passenger cars from that era would all have been sold brand-new with two keys. If you’ve bought the car second-hand with just the one key, you can contact a Mercedes-Benz dealership, quote the car’s VIN and the dealer will be able to order the correct key and electronically code it to work in your car. It could cost several hundred dollars, however.