W205 Auto forgotten how to change up

[BEA76]

My W205 C220d, Nov 2015 now with 43,000 on the clock.
After a 600 mile trip for weekend in lake district, nearly home turning off motorway the gearbox became reluctant to change up. Down shifts all OK, but whatever mode ( E, C Sp etc) box was in upshifts were all at 2500 rpm and less than smooth. No warnings on service assyst display.
After a 2 hour stop and carrying out the gearbox reset routine it behaved itself for the remaining hour, 45 miles of journey.
No obvious leaks, sump tray is dry. I am more than a bit cautious of driving further without more info.
Of course car is 3 months out of warranty

Any ideas learned folks? Is this a precursor of problems to come or one of those software issues that just happen???
Appreciate any comments.

 

[Flyinspanner]

Is the ATF fluid, clear, bright red, and smelling ‘sweet’, and to the correct level?
(If at all murky/brown/smells burnt or like treacle, then you have an issue)

Do you have an icarsoft you can check codes? - or see if anyone near you could let you borrow one?

I’d maybe get an indie to do a precautionary ATF & filter change, with good check on the fluid removed, and a STAR check on stored codes.
(Maybe conductor plate? -sticky solenoid?)

Hope it’s just a transitory glitch

 

[slade1]

Electro plate?

 

[DSM10000]

At 3 months out of warranty it is worth having a word with your MB dealer as it possible they may look favourably on a goodwill repair?

 

[BEA76]

At 3 months out of warranty it is worth having a word with your MB dealer as it possible they may look favourably on a goodwill repair?

Good idea, thanks

 

[Flyinspanner]

At the very least, they may do a free star diagnostic, and massive discount.
Well worth a polite approach.