Help needed… Radar/Sensor issues W205 C220D (65 Plate)

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bob mushroom

Member
Joined
Jul 4, 2004
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Travelling in March 2020 (2 days before lockdown) my car lost power and all sensors became operative. I drove to destination and on return all worked again until I got the warning Active Blind Spot Assist inoperative.

This would come on/stay off intermittently along with PRE-SAFE functions limited see owners manual.

In July the Active Blind Spot assist inoperative was always on. In September my Distronic started to intermittently become inoperative along with the lane keeping assist, until know in December both are always inoperative.

I have had my car serviced in November and a diagnostic done which said fault Radar 3 great……

The problem is the garage do not know which radar 3 is…. Can anyone help? I do not want all bumpers off and labour costs rising on a hunt!
I am suspicious of what the fault may be though with the intermittent on/off and the apparent daisy chain of failures.
I know it will cost money to fix but I want to know all cheaper than full replacement avenues have been explored

Fuses?
Wiring?
Sensor check?

Can anyone offer any suggestions to help the car perform as it should?

Thanks in advance
 
Was it a Merc garage that serviced and diagnosed the car?
 
something like that probably needs to go on STAR for diagnosis.
 
Looks like I will have to bite the bullet and pay for mb to find then replace whatever it is....
 
Looks like I will have to bite the bullet and pay for mb to find then replace whatever it is....
Why do you think MB will be more competent than a good Independent?

If you post your location then members may be able to suggest other specialists who may be better suited to the task.
 
My understanding is that the three systems that you mentioned as having reported faults (Distronic, blind spot, lane keeping) actually use different sensors. Distronic uses radar sensors at the front (may also use the multifunction camera, I suppose), blind spot detection uses side-facing radars at the rear, and lane keeping uses the multifunction camera. So one sensor failure is unlikely to cause intermittent error reports in all 3.

Do the systems fail when you are driving in the same locations? Be aware that the radar-based systems will automatically be turned off in certain locations to avoid interfering with fixed systems such as military or aviation installations that use the same frequencies - this always happens with mine driving down the M11. Also, it is possible that detected interference (fixed installations or other vehicles with radar sensors) is causing temporary errors that are not indicative of actual sensor faults.

Whenever I do a system scan with Carly, it always reports a logged radar fault which I put down to the causes above: my Distronic and blind spot assistance work well. So you are right to tread carefully before starting to replace anything.
 
Having
Why do you think MB will be more competent than a good Independent?

If you post your location then members may be able to suggest other specialists who may be better suited to the task.
Having taken it to a indy in Huddersfield they were only able to advise a fault on RADAR 3 after diagnostic. Problem is there is no telling what RADAR 3 is. Any suggestions?

My understanding is that the three systems that you mentioned as having reported faults (Distronic, blind spot, lane keeping) actually use different sensors. Distronic uses radar sensors at the front (may also use the multifunction camera, I suppose), blind spot detection uses side-facing radars at the rear, and lane keeping uses the multifunction camera. So one sensor failure is unlikely to cause intermittent error reports in all 3.

Do the systems fail when you are driving in the same locations? Be aware that the radar-based systems will automatically be turned off in certain locations to avoid interfering with fixed systems such as military or aviation installations that use the same frequencies - this always happens with mine driving down the M11. Also, it is possible that detected interference (fixed installations or other vehicles with radar sensors) is causing temporary errors that are not indicative of actual sensor faults.

Whenever I do a system scan with Carly, it always reports a logged radar fault which I put down to the causes above: my Distronic and blind spot assistance work well. So you are right to tread carefully before starting to replace anything.

This is what I believe also, seems more electrical wiring/fuses rather than sensor. I am worried that the work will be carried out on an easier to solve basis causing me a lot of money. BTW the fault is constant now so not interference.
 
Having

Having taken it to a indy in Huddersfield they were only able to advise a fault on RADAR 3 after diagnostic. Problem is there is no telling what RADAR 3 is. Any suggestions?



This is what I believe also, seems more electrical wiring/fuses rather than sensor. I am worried that the work will be carried out on an easier to solve basis causing me a lot of money. BTW the fault is constant now so not interference.
Find another MB Specialist, hopefully, another member will be able to recommend someone close by,

I very much doubt that a fuse is causing this, a fuse is operative or not unless it is making very poor contact.
 
Any independent would need to have and be competent using, STAR diagnosis.
Generic code readers are always limited in the depth of info they return.
 
Have you checked your battery?
My SLC was behaving like that and a new battery cured it. Even after a full charge it was only showing at most 12v, sometimes only 11.5v.
 
Have you checked your battery?
My SLC was behaving like that and a new battery cured it. Even after a full charge it was only showing at most 12v, sometimes only 11.5v.
The battery was changed just recently - I was hoping that would fix the problem but alas......
 
Hello Bob,

Please could you let me know the outcome of your fault. I have the same 3 fault messages and I have had the system diagnosed tested. They say that the front nearside (passenger) radar sensor is faulty. But looking a what 'FiveAlive' has posted it looks like the 3 faults use different sensors.

I was thinking of purchasing a new radar sensor from ebay (from Germany) for £200. The garage wanted to charge my £480 for the sensor and £670 in total for installation

However, at the moment things just don't add up.

It would be good to know your solution.

Regards John
 

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