I have a 99 ML320. A couple months ago, every couple of days the car would either not shift up into a higher gear, stuck in 2nd gear it seems, or get stuck in 3-4th gear, and will not downshift when vehicle has slowed down to a stop. This means at a stop light it would accelerate extremely slow due to the higher gear. I would then turn the car off and turn it back on, and the problem would be gone. Back to normal.

A couple of days ago, the problem has came back, but this time, it is here for good. I tried turning off and back on to no avail. So right now, it wont upshift past 2nd gear. I initially presumed it was limp mode related, but my friend says there is a code in the tranny cpu saying that it has to do with the RPM sensor. I could get the exact codes if that would help.

Have anyone else experienced this problem? If so, how was it resolved?

In checking w/the local MB dealer, the tech suggested it could be the crank sensor. As our temps have been around 92 degrees, he mentioned that extreme temps can active the problem. The air mass was replaced several days ago.

 

can you read the fault code first?

it has nothing to do with the RPM sensor for wheels and crankshaft position sensor.

 

I had the same problem and the Mercedez benz dealer changed all sorts of parts without fixing the problem. I eventually took it to a foreign car mechanic who found that it was the electronic alternator. The alternator on these vehicles has a regulator thatmodifies the voltage and if it is bad will send all sorts of malfunctions to the cpu. Since having the alternator I haven't had any problems.