DCT overheat on 2015 35Is

A

Alan Crook

Member
I have a 2015 35Is that's only done 25000 miles and the last few weeks i have had the Amber DCT gearbox overheat light coming on when in stop start traffic almost straight away. I can do 60 miles on the motorway then come off the slip road and as soon as it does a few 1st to 2nd changes the light will come on. No transmission fluid leaks but could it just need a gearbox service or a dodgy sensor as box seems to work fine still but have noticed a slight whine now in 1st,2nd and 3rd, goes silent after that. DCT replacement i guess is £1000's but love the car so whatever it needs will be done. Anyone else had issues? Thanks Alan
 
That seems low mileage to be having problems.
How do you know that it hasn’t got a leak?
Do you have a code reader?
Do you have a decent independent garage that could take a look at it?
 
Usually DCT overheat is caused by low transmission fluid level..you have to undo the fill plug to see if fluid dribbles out..it’s a complex affair that requires BMW s/w tools to fill correctly…

Interrelated to this is that the clutch packs can wear out when abused and/or low fluid level..resulting in overtemp warning..

FWIW I think you need to prepare for a big bucks experience…

It may just may be a sensor issue but….
 
I seem to recall that a leak on the DCT is actually a known issue, looking back in the history of mine it was done years ago.
My local independent had told me that there is a ZF service kit they get for doing an oil change, with gasket as they drop the bottom sump off.
I'd start there.
 
Dct leaks are a common issue. Unfortunately you probably won't notice any sign of oil on the floor under the car. The plastic undertray catches and hides the leaks.
 
Just thinking out loud, but might it be worth a change of the dct fluid & see if the problems are gone?

Could be it’s just low on fluid / ready for a service anyways.

Might be cheaper to do that than have a full on inspection.

Another thing you could do yourself is run diagnostics from a decent odbII unit. Pretty sure my Autel Maxicom does these level diagnostics.

It’s a few hundred for a DCT service, similar for the scanner - but getting the Pros in to investigate will soon rack up a lot more IMHO.

If you are not too far from Reading I can do this for you (free)
 
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