It only appeared to happen twice about 3 months apart. While driving my Merc. S280 2001/2 it seemed to cut off and when I depressed the accelerator their was no effect on it. I stopped put the gear into park and they back on drive and the problem disappeared.
Wiseman

 

Hi,
Your car has an electronic accelerator (no accelerator cable/linkage between you foot and the engine just electronics).
This enables the power to be cut if exhaust emmissions threaten legislation. This cutting of power is known as "Limp Home" mode.

Emmissions can be threatened during an overtake, acceration situation if there is something wrong with the engine. Any such defect is detected by the engine management system and stored as a defect code DTC in the EMS.
You need to get the codes in the EMS read (including the flash memory=conditions prevailing in addition to the Long term Fuel Trim LTFT values) using a scanner so that the cause of Limp can be determined.

Did your Check Engine light (CEL) come on? I suspect it did.

You are fortunate that the system reset itself with an ignition "off" cycle. This is not always the case dependent upon the nature of the problem.

I suspect that this is an early indication of a MAF problem. Codes P0170/0173 and high LTFT values will confirm.
If it is the MAF this is a simple DIY job, (if relatively expensive part 200USD ish) to change. It is sometimes possible to clean the MAF rather than replace it but this doesn't always work dependent upon the nature of the fault.

You don't state vehicle mileage. MAF problems usually show up at about 80k.

Stuart

 

I would have the computer checked also, there could be a problem with a sensor. Or the drive by wire sensor to be exact. I have the same setup and it's great, but I never heard of a failure in the drive by wire. So I would have it checked and also look elsewhere.

My MAF just popped a check engine light and I didn't have the problem you discribed before the light came on.

I am going to try CRC's MAF sensor cleaner. I read a article on the product in Popular Mechanic's and they give it high praise and it really works. It a lot cheaper then the $400 for a new MAF. As the article said, the dealers tell you these sensors can't be cleaned, but they also have a bigger interest in selling you a new one. If it turns out to be the MAF. Install it yourself, it is a DIY job, takes about 20 minutes, if that. I got a little over 30K miles out of it, this second sensor. The OEM one lasted 23K miles, so I guess I got my monies worth out of the second one.

Interestingly Mercedes is the first car I have owned that MAF's have failed. I usually drive a car to 75K miles and buy a new one and never had a MAF fail on other makes???

The reason I mentioned a sensor problem. I had a 911 Carerra a few years back, and the engine would die while driving. I'd pull over and let the engine cool down a bit, as mine was air cooled and they did run hot. The problem turned out to be a sensor on back of the engine, which overheated due to the engine heat. The car was an 86 and the sensor was the factory installed one, so it lasted quite a while. This sensor was $425 as I remember and another $300 to drop the engine to replace it.