Hi there,
We've had our '17 GLC350e for about three years now and it is starting to act up a bit lately..

On a longer drive a few weeks ago, we got an error telling us to stop the vehicle and let idle in P for some time.
We did so and a friend of us recommended to continue the journey in Sport mode so the engine wouldn't switch on and off.
A local MB guy recommended to check the alternator charge voltage and check the battery capacity of the starter battery.
Charge voltage was fine but the battery failed the charge/discharge test so we got a new one installed. The charge voltage was/is a little over 14V so seems okay.

Now, in the past week, it have started to display 'MALFUNCTION' in the display together with a symbol of two meshing gears.
The clutch will almost completely disengage so very little torque is transferred to the wheels.
Going at speed or uphill in this mode is near impossible.
If you press the accelerator the engine revs but the car ain't moving anywhere near as much as it should. It almost feels like driving around in Neutral..

Switching the car off and on while sitting in the car doesn't make any difference.
Switching off the car, locking the door just to unlock the door again start the car and put in in Drive and everything appears normal. Could it be software ?

Driving long distances usually triggers the fault.
Charging the main battery (also the new one) seems to keep the malfunction at bay for some days.
Doesn't seem to relate to up/down shifts as the error appears even when cruising along on flat roads.

What gives?
Anyone heard of this behavior before ?
Is this a software error?
Is the gearbox/clutch about to give up on life? I hope not..

We asked around at the local dealerships but nobody knows what it could be and I am a little hesitant to just having them start to replace parts at random to see what works..

Do anyone have any idea where to start looking/probing?

 

A few questions:
Any codes stored? Needs to be scanned with a good reader. Preferably with xentry
How many miles?
Trany service Yes or No?
If yes who and how it was done?

If you have access to xentry you can look what stored in the block Y3/8
If there is no errors I would perform adaptation
After its done it should look like this: