Cls 350 cdi gear box problems

[Ian bulley]

Hi all, quick update.

Today it played up on the way home from work and I managed to get it into Waterhouse mercedes in Braintree as they we closest. Without turning the car off they drove it agreed there was something going on and managed to get a code relating to the dpf pressure sensor?
So its going in Monday for a new one fingers crossed it does the trick.

 

[JBell]

Hi all, quick update.

Today it played up on the way home from work and I managed to get it into Waterhouse mercedes in Braintree as they we closest. Without turning the car off they drove it agreed there was something going on and managed to get a code relating to the dpf pressure sensor?
So its going in Monday for a new one fingers crossed it does the trick.

Mine did exactly the same, replaced the sensor and all back to normal

 

[alexanderfoti]

Was going to say, sounds like the engine is in limp mode. Limp mode does odd things to gearbox changes but the 3k rpm rev limit is the giveaway!

 

[Ian bulley]

Hi all sensor has been replaced so fingers crossed. I'll know if its done the trick in a week or so, it never went more than a week without playing up. Waterhouse mercedes in Braintree have been very good and very helpful.
Thanks again everyone I will update in a few weeks.

 

[Ian bulley]

So its been a few weeks now since the dpf sensor replacement and the car has been great. So far no issues so I think its done the trick. Thanks for all the help and advice everyone, I hope this thread will help someone else in the future if they find themselves with a similar problem.

 

[Jenny Tills]

Hello all. All this happened to me this morning. From cold start up, it has weird gearchanges, no kick down, no power like it should have.
Hopefully, thanks to this ace forum, it is the DPF sensor. Fingers crossed!

 

[rich.g.williams]

Hello all. All this happened to me this morning. From cold start up, it has weird gearchanges, no kick down, no power like it should have.
Hopefully, thanks to this ace forum, it is the DPF sensor. Fingers crossed!

Sounds like the engine is sulking then rather than a transmission problem.

How about the engine management light - has that come on?

You are going to want to read the OBDII codes most likely.

 

[Jenny Tills]

Hi. No warning lights of any kind. I switched the engine/ignition off and on and it briefly returned to normal only to start with the aforementioned problems again.
I will book it in with my local Mercedes specialist on Monday morning for a proper diagnosis and remedy.
Thanks very much.

 

[rich.g.williams]

Hi. No warning lights of any kind. I switched the engine/ignition off and on and it briefly returned to normal only to start with the aforementioned problems again.
I will book it in with my local Mercedes specialist on Monday morning for a proper diagnosis and remedy.
Thanks very much.

Switching the engine/ignition off and on is a good move - it likely resets the fault picked up by the ECU engine computer (or other management computer) but as soon as the ECU (or other computer) gets a chance to look around it finds the fault again. Its response it seems is to put the engine and the transmission into this sort of gutless "safe mode"

I don't know this car or engine so pure guesswork on my part but something like a faulty sensor would do it, take your pick camshaft sensor, O2 sensor etc.

Surprised the Engine Management light is not coming on, and the dash display is not nagging, so maybe its something not quite engine. No idea about what a DPF fault would do but - could be.

Then the transmission, but you say that it does still change through the gears just kind of weirdly.

The weird behaviour as you mention "weird gearchanges, no kick down, no power" all likely/typically part of the gutless "safe mode" thing.

Surely your local Mercedes specialist will quickly find an explanation hopefully at not too much cost.

Maybe not drive the car too many miles before you get it to the specialist.

 

[onefortheroad]

Hi. No warning lights of any kind. I switched the engine/ignition off and on and it briefly returned to normal only to start with the aforementioned problems again.
I will book it in with my local Mercedes specialist on Monday morning for a proper diagnosis and remedy.
Thanks very much.

Usual suspects, exhaust back pressure sensor or differencial pressure sensor.

 

[Jenny Tills]

Switching the engine/ignition off and on is a good move - it likely resets the fault picked up by the ECU engine computer (or other management computer) but as soon as the ECU (or other computer) gets a chance to look around it finds the fault again. Its response it seems is to put the engine and the transmission into this sort of gutless "safe mode"

I don't know this car or engine so pure guesswork on my part but something like a faulty sensor would do it, take your pick camshaft sensor, O2 sensor etc.

Surprised the Engine Management light is not coming on, and the dash display is not nagging, so maybe its something not quite engine. No idea about what a DPF fault would do but - could be.

Then the transmission, but you say that it does still change through the gears just kind of weirdly.

The weird behaviour as you mention "weird gearchanges, no kick down, no power" all likely/typically part of the gutless "safe mode" thing.

Surely your local Mercedes specialist will quickly find an explanation hopefully at not too much cost.

Maybe not drive the car too many miles before you get it to the specialist.

Yeah. Left the car at work, and borrowed a van. I don't want to compound the issue. Hopefully it's a sensor somewhere and not another massive bill.
I've already had the dreaded oil cooler O rings replaced at great expense.

 

[Jenny Tills]

Usual suspects, exhaust back pressure sensor or differencial pressure sensor.

Thanks, yeah, lets hope so!

 

[ajlsl600]

Thanks Matthew ill relay that to the garage in the week, it has been on the diagnostic machine and didn't show any faults but it definitely isn't right other than that the car is amazing such a shame obviously the reason it was traded in.

Make sure it's a notified fault before warranty expires then its current until dealt with for warranty purposes
Conductor plate most likely issue.i see ref to DPF and sensors, a faulty sensor wud have to throw a code right? Is that not the whole point of diagnosis.

 

[rich.g.williams]

I've already had the dreaded oil cooler O rings replaced at great expense.

hmm - not had the oil cooler O rings drama yet - maybe something to look forward to for the future then lol

 

[onefortheroad]

hmm - not had the oil cooler O rings drama yet - maybe something to look forward to for the future then lol

Do you drive an om642 engined motor ?

 

[rich.g.williams]

Do you drive an om642 engined motor ?

My last Mercedes was a diesel but this one is a petrol with the m271 engine - never the V6 om642 engine.

Just empathy and some understanding of O rings in difficult places.

 

[JBell]

Hi. No warning lights of any kind. I switched the engine/ignition off and on and it briefly returned to normal only to start with the aforementioned problems again.
I will book it in with my local Mercedes specialist on Monday morning for a proper diagnosis and remedy.
Thanks very much.

They need to "Live diagnose it" when the problem is there, this is how I found my EGR to be faulty, if I turned the car off then back on the fault went away and there was no log of it.

 

[Jenny Tills]

They need to "Live diagnose it" when the problem is there, this is how I found my EGR to be faulty, if I turned the car off then back on the fault went away and there was no log of it.

A little update, I have had to take the car home ready for when it goes to its garage appointment and when I started it low and behold the engine management light came on. I was actually quite relieved because at least they will be able to pin point the problem. Hopefully!
Cheers.

 

[onefortheroad]

A little update, I have had to take the car home ready for when it goes to its garage appointment and when I started it low and behold the engine management light came on. I was actually quite relieved because at least they will be able to pin point the problem. Hopefully!
Cheers.

Light comes on after 5 or 6 consecutive same fault codes .

 

[Jenny Tills]

An update for anyone who wants to know....
The cause of my limp mode and engine management light was a dodgy exhaust pressure sensor.
All fixed now thanks to my local Merc specialists.
Glad it wasn't something more serious.
Thanks to this forum for all the knowledgeable people calming my gearbox fears!