W205 gear selection issues

[Jbaz]

Hi there. I have a 2019 plate petrol 9tronic c class. Car has been running great since we got it last August but over the past 24 hours, has been acting strange when driving on motorways at 70mph.

Normally at these speeds, it is well up to 9th gear. Usually around 65mph.

Was driving last night on the motorway for about 10 mins and saw average fuel economy was only around 25mpg and noticed the car was in D7 at 70mph. No matter what happened, car would only shift up to 8th and 9th manually via paddle. Even when accelerating hard, it would drop down okay but then only climb and plateau at 7th max.

On normal driving conditions, the car is in 7th gear at 45ish mph so to not shift up at all even when getting to 70 or 80 is not normal behaviour for our car. Even in ECO mode, the car will now not change up by itself to high gears. Keeping at 2500-3000 revs at that speed is not economical.

I’ve checked these forums and have tried a couple of things such as resetting auto transmission today, to no avail. I am wondering if this is a wider electrical or gearbox issue.

The car is due a service in 2 months and has full service history. It has not received any recent dealership updates unless for some reason it’s happened remotely over night. I have read a couple of other posts about diesels with NOx emission updates but ours is a petrol and still not even shifting to higher gears beyond 75mph. Also don’t think it’s the cold weather as it wasn’t doing this when it was -5 degrees and has been quite mild yesterday and today.

Any help or advice is greatly appreciated. We have a 2 year private warranty arranged through non-MB dealership so would probs have to diagnose any issue ourselves and claim any repairs through them.

Cheers!

 

[Blobcat]

Hello and welcome,

If it was a diesel it could be trying to do a DPF regeneration, holding a lower gear and higher revs during the burn off.
Although I think they’re even fitting a GPF (Petrol Particulate Filter) now so that could be doing the same.

 

[Srdl]

Hello and welcome. Yours will have a GPF but they don’t usually havE problems with regeneration like diesels but it sounds like yours may have a problem,

Have a look at this link if you want to read up on the difference between DPF and GPF and how they work.

Infineum Insight - Gasoline particulate filters

Regulations curbing vehicle tailpipe emissions are being introduced and/or tightened the world over to help improve air quality. Infineum Insight looks at the automotive industry’s growing use of gasoline particulate filters as one method of compliance.

www.infineuminsight.com

 

[jani-h]

Hi,

I have exactly the same problem. In addition, I've noticed that the cooling fan is now quite often ON after driving (it didn't used to be ON that often before).

Did you find out what was causing the problem?

 

[mioba]

One post wonder

 

[evelina]

Hi I'm new here as desperately trying to find a solution to my problem. I have the exact problem as described above.
Gear shifting of higher gears is a nightmare , it shifts it ok till it gets in 5th and after that it is stuck for ages in a gear that's too low for the speed.

I I can change it manually using the paddles but it doesn't do it automatically.
The worst of it is it sometimes works ok for a day or two and that it doesn't again for 2 weeks.

When I don't use paddles fan comes on as soon as I park and it goes for few minutes to cool the engine down.

I had it back with dealer ( nor Mercedes) twice and they told me there is nothing wrong with the car.

I have than took it to Mercedes and they have told me to reconsider my style of driving aka " you stupid woman need to larn how to drive".
I'm running out of ideas of what to do next... any help would be much appreciated.

 

[Srdl]

Hi I'm new here as desperately trying to find a solution to my problem. I have the exact problem as described above.
Gear shifting of higher gears is a nightmare , it shifts it ok till it gets in 5th and after that it is stuck for ages in a gear that's too low for the speed.

I I can change it manually using the paddles but it doesn't do it automatically.
The worst of it is it sometimes works ok for a day or two and that it doesn't again for 2 weeks.

When I don't use paddles fan comes on as soon as I park and it goes for few minutes to cool the engine down.

I had it back with dealer ( nor Mercedes) twice and they told me there is nothing wrong with the car.

I have than took it to Mercedes and they have told me to reconsider my style of driving aka " you stupid woman need to larn how to drive".
I'm running out of ideas of what to do next... any help would be much appreciated.

Is yours petrol,or diesel? If it’s diesel, it sounds like a DPR regeneration, which is normal,

May be unrelated but my fan has been running on for a few minutes after I turn the engine off. It has done it a couple of times before and always after I have got water in the fan controller (usually by going through some deep puddles or a water splash/ford). Now sorted itself again after a couple of days. Have you been through a lot of water recently - hard to avoid down south with the rain we’ve had? It may just dry itself out

 

[evelina]

Is yours petrol,or diesel? If it’s diesel, it sounds like a DPR regeneration, which is normal,

May be unrelated but my fan has been running on for a few minutes after I turn the engine off. It has done it a couple of times before and always after I have got water in the fan controller (usually by going through some deep puddles or a water splash/ford). Now sorted itself again after a couple of days. Have you been through a lot of water recently - hard to avoid down south with the rain we’ve had? It may just dry itself out

It is petrol, I haven't been through water it has been happening for 4 months on and off. When I use paddles to to to higher gear it suggest even higher gear. For example normally car shift to gear 6 around 38 40 an hour now it only goes to 6 when I'm driving 50-55 but when I switch it to 6 manually it comes with a suggestion in green for a 7th when I'm in the manual mode. I'm not an expert at all but I feel just that itself indicates that there is something wrong.

Car generally lost the power and even in Sports mode or Sport+ is just extremely slow and sluggish.

 

[Srdl]

That’s clearly not right, as you know! I think you need to see a Mercedes specialist, an independent, not a Main Dealer. They will use experience and common sense rather than just plugging the car into a computer and then making guesses. Tell us where you are and someone may be able to give you a recommendation,

 

[evelina]

That’s clearly not right, as you know! I think you need to see a Mercedes specialist, an independent, not a Main Dealer. They will use experience and common sense rather than just plugging the car into a computer and then making guesses. Tell us where you are and someone may be able to give you a recommendation,

Thank you sounds like a plan as to be honest that was my next step. I'm in Manchester any recommendations would be much appreciated

 

[Srdl]

Thank you sounds like a plan as to be honest that was my next step. I'm in Manchester any recommendations would be much appreciated

OK, most of the ones I know are down south but others will know of someone @Blobcat

 

[Blobcat]

OK, most of the ones I know are down south but others will know of someone @Blobcat

Wrong side of the Pennines

@EmilysDad knows a few

 

[EmilysDad]

Wrong side of the Pennines

@EmilysDad knows a few

Daventy & myself go to see John @ http://jbmbury.co.uk/

 

[evelina]

Daventy & myself go to see John @ http://jbmbury.co.uk/

Thank you

 

[jani-h]

Hi,

Small update to my problem: After few days the problem (=not shifting automatically to highest gears & motor cooling fan on after parking) disappeared, and has not appeared since. That is, the car has been fine for a month or so.

Thinking back, it was quite rainy time - with a lot of puddles - when the problem emerged.

 

[Srdl]

Hi,

Small update to my problem: After few days the problem (=not shifting automatically to highest gears & motor cooling fan on after parking) disappeared, and has not appeared since. That is, the car has been fine for a month or so.

Thinking back, it was quite rainy time - with a lot of puddles - when the problem emerged.

I’ve certainly had the cooling fan issue two or three times when I’ve got it really wet but never had the gear change issue. Fingers crossed yours behaves now!