722.9 'Limp' mode but no fault codes recorded

[FlintCLS350]

Hello

I have a 2008 CLS350 (Petrol) with 70K miles - dealer and independent M.B specialist serviced since new with stamped service records etc. It appears to have had a 'Easy' life given its exterior/interior condition and on road performance which is flawless except for the following.
Each week I complete a 80 mile round trip and about every fifth/sixth time that I go out to do that the car will inexplicably go into limp mode (Stuck in 2nd gear?) when I pull way gently from a stop, eg., @ traffic lights. When I pull over to the kerb, stop engine and restart it the car/transmission operates perfectly as if nothing had happened and it could be a month or so before it happens again. The transmission (with VGS2 conductor plate) has recently been serviced by an M.B independent (Correct oil/filter etc) however the fault has occurred twice since that time. Car has a new battery.
I've bought a 'icarsoft MB11' scanner but could not bring up any fault codes nor could the M.B independent specialist or an automatic transmission expert (50 years exp.) who has had vast experience with M.B transmissions including the 722. No one can induce the symptom and in the absence of fault codes basically suggest that nothing can be done except monitor the situation. As it worries me knowing there is an underlying problem which is unidentifiable any assistance as to what I should do would be appreciated.

Thank you in advance.

 

[onefortheroad]

Can it be the engine that's putting the transmission into limp mode. ?

 

[MJJ]

Two thoughts from me:
- You mention new battery, but have you checked the charging system voltage when the engine is running? Low voltage causes all sorts of odd errors, though I would expect them to flag on Carsoft. You can check this easily by ignition position 1, then press trip reset three times in quick succession. Then start the car.
- Odd behaviour with no stored errors *could* suggest the behaviour is user commanded. Is there any mode/button/selector position in the car that would correctly cause this transmission behaviour? I am wondering if you have a failing switch (winter mode) or gear selector position sensor that means the car thinks you have selected some sort of operating mode. Does the transmission-mode and gear-selected displays either side of the odometer change when the car misbehaves?

Martin.

 

[FlintCLS350]

Thank you 'Onefortheroad' and 'MJJ'. I will probe the points that you mention.