Distronic weirdness - W212 E350 CGi (2010)

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jjcodex

Active Member
Joined
Nov 30, 2008
Messages
186
Location
Exeter
Car
S350 W222 SL55 AMG
Hey all,

I have an E350cgi which I have had for rather a long time now, and I am having increasing issues with my Distronic radar guided cruise control.

In a nutshell, as most will know, the Distronic system can temporarily shut itself down in very adverse weather conditions (due to natural and unavoidable interference). This triggers a polite message that advises you that it is unavailable, and a further polite notice when it is back up and running again.

I understand that the above is norma. HOWEVER, my car is now putting itself into this state with alarming regularity, and even on dry sunny days. In fact, it has now got to the point where almost every journey will be greeted at some point with this message, and on some occasions on multiple times a journey. Also - when it is not in fault, it works fine.

The issue I have is that when taken to Mercedes, they read the computers fault codes, and find none (as the car doesn't appear to think there is a problem beyond bad weather!)

I have ruled out external sources of interference as there is no rhyme or reason to when it enters this state.

Has anybody else experienced this? And if so, how did you cure it?!!?!

Help!

Thanks in advance

James
 
It's worth giving the sensors a good clean. The centre one behind the grill isn’t too difficult to get at, but the others that are behind the bumpers will be more difficult.

FWIW, my 2012 E63 used to give the message occasionally, especially when coming down the exit ramp of a particular multi-story carpark, but I never did get to the bottom of it. Maybe it’s something daft like leaf debris trapped between one of the sensors and the bumper?
 
Thanks Phil

I will have a good look but they were apparently cleaned by MB not so long ago (I wonder whether the only cleaned the middle one as opposed to the hidden ones....
 
I wonder whether the only cleaned the middle one as opposed to the hidden ones....
Probably - I never properly investigated how to get to the ones behind the bumpers, as it looked like it may require a fair degree of dismantling.
 
FWIW, my 2012 E63 used to give the message occasionally, especially when coming down the exit ramp of a particular multi-story carpark, but I never did get to the bottom of it.

Condemned to spend the rest of your life on a multi-storey car park exit ramp!
 
Yes, I must admit that has allowed me to ignore them as well. I admit that it was only recently that I knew that they existed at all! I laboured under the impression that it only had the single sensor behind the grill!

I will have a word to see how easily they can be reached, or as you say whether it requires the bumper removal as I suspect it does.

JJ
 
it has now got to the point where almost every journey will be greeted at some point with this message, and on some occasions on multiple times a journey
Are these journeys along the same stretch of road or very close to the same general local area? I ask because the system recognises certain areas were use of this type of radar is prohibited (radio telescopes/radar installations/certain airfields etc), it also detects electromagnetic interference. Perhaps from some new or mobile installation?
 
Hiya - no they are not - and moreover they are regularly erratic in where they occur (I live n the Westcountry, so there are no real sources that could reasonably explain them, and they also occur in places where they have not occurred in the past).

Also, as an aside, mine is a very early W212, so I would be honestly surprised if it had that level of sophistication.

JJ
 
Don't know if it helps, but I had a fault where Distronic, Blind Spot Assist and Variable Cruise would throw up various errors occasionally but not leave any fault codes.
This is on a 2011 E250.
This being on a car that was under Mercedes used car warranty, they went to town on it and finally found a fault with the control module.
Turns out at some point moisture had got into it causing some corrosion as therefore intermittent faults.
They discovered this after replacing all bumper sensors and radar unit
 
Hey Cowley,

ahhh the good old days of warranty repairs!

To be fair I think mine had a replacement control unit and main sensor (the one behind the grille) back when it was still under warranty but that was some time ago.

The rest of the system (blind spot assist etc) all stays working fine, but as you say - that doesnt rule it out as a source of fault! Thanks for the suggestion.

Out of interest, has anybody actually ever attempted to find the sensors behind the bumper?

Don't know if it helps, but I had a fault where Distronic, Blind Spot Assist and Variable Cruise would throw up various errors occasionally but not leave any fault codes.
This is on a 2011 E250.
This being on a car that was under Mercedes used car warranty, they went to town on it and finally found a fault with the control module.
Turns out at some point moisture had got into it causing some corrosion as therefore intermittent faults.
They discovered this after replacing all bumper sensors and radar unit
 

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