So here is an interesting one. Out of nowhere Active blind spot, cruise control and pre-safe stopped to work. Interestingly enough parking sensors work, and the LCD shows how it sees the car in front, So obviously all sensors are good, just something goofy - software glitch?
Any one knows how to reset it, hopefully that is all it needs, and no I really need to avoid the dealer.

Checked all the fuses, they are ok. I unplug the negative on the battery for 30 minutes or so, not sure if the positive(+) needs to be un-plugged too. (especially how hard it is to get to the battery)
This is 2013 GL550

Thank you for any advise.




Here it shows how it sees another car, but somehow its not working

Not sure on how to resolve your symptoms but there is a small backup battery in the car, hidden in the rear compartment. I'm not sure disconnecting both batteries is advisable, there are a whole bunch of settings that can get screwed up and only reset at the Mercedes dealer. Hopefully someone more knowledgeable than me can weigh in.

Got the same msg 2 months ago. Gently cleaned all the button sensors on the bumpers. Gone on next start up and hasn't returned. Will ask service advisor next month if there are any stored codes.

Could be the auxiliary battery - for whatever reason the aux battery powers some of the sensors as well as the start stop function

while driving on interstate, mine would do the same thing, everytime there was a ford near by, apperently its raders throw of merc's sensors, there has been some write up on this. i know it sounds silly but my problem went away when i drove past the other vehicle.

ok, so I found this local shop (owned by ex Mercedes Tech in MotorWerks in Barrington IL), they found a front right sensor defective (not working).

Price for this was little steep, so I said let me look at it.

Surely, indeed, front right radar sensor got a water damage, due to broken housing. How did it happened? Very poor design of the module. I will post pictures shortly

Anyways, I will try to open it up and try to repair the electronics

Find a used one. Most likely plug and play.

Saw that the broken sensor was your issue, but FWIW, my Active Cruise was acting up, and just disconnecting the MAIN battery for a while fixed it - cruise worked fine, but the red lights display on the dash stopped appearing, no error codes or warnings were displayed tho. Kinda forgot about it, but when I changed JUST the main battery (did not disconnect the aux battery when changing the main), I guess the system reset on it's own, just from disconnecting the main battery for a while during the change - yeah - it was probably more than a half hour, cuz that damn battery is a bit hard to work on under the seat, and I was extra careful, cuz it would have been really easy to bridge the terminal to the metal frame under there, with the tight quarters and a ratchet!

OK, All fixed now. Defective Sensor Found, and repaired, not replaced. It was defective (due to water damage) So 2 capacitors and a coil was replaced. Cost? Capacitors are probably fraction of a cent, and coil maybe a nickel at DigiKey, and since I do electronics repair, its simple soldering. Here are some pictures with annotations.
I am thinking dealer would take at least $1K from my wallet, with some made up story of taking whole bumper apart, programing, calibration etc....

I am not sure if this will help anyone, this was very odd problem, but who knows Bottom line, anything (well almost anything) can be fixed, just little patience and little soldering skills.

Let's start where its located. Its super easy access, just use flat plastic flat head







Here is the sensor and where it cracked and water/moisture got in




After opening it, well self explanatory






This is after cleaning it, and replacing components





And here is a look at all that is inside







Any Questions ?
)

Man! Impressive! This is a whole other level of DIY! Not "worth" it in time maybe,(I like to do time consuming fixes sometimes too for the sport of it - but not fine soldering!! ha) but always quite satisfying, right!?! Well done! I think there is also a joke here somewhere about that single sensor having more computing power than my entire first car......(edited - see below - probably worth the time - haha!)

Then again I couldn't help myself - had to google that sensor part - looks like Object Sensor 000-905-45-03-27 - List Price $795 - online, $548, Ebay $250

Wow - just wow - you owe yourself a few beers!!! and you're $1k estimate from the dealer may have been low...... Again - nice work!

I owe a clarification on this post. At first I claimed its a "poor" design. Well its somewhat true, but here are the facts. 2 years ago, my wife swirled off the side street and hit a tree with about 5-10 mph. No Damage, what so ever, just a small crack on the bumper. We did not report it to insurance. But now I see that little "bump" caused a crack in the module, which did not go bad right away, but it took 2 years for water/moisture to work its magic.
So is it really bad design? that 5 mph will cause a sensor to break? You will be the judge.

Now I have a scoring on cylinder 1 and 5, where knocking noice will require the engine replacement or re boring
any ideas where I can get it done?
Andrew

Please state what car and mileage?

Dealer don't fix these modules, just install one and program it in the CAN bus.
The squares you see on the board are phase array Ghz antennas for directivity. You can Google it.
Engine scoring is fixed by sleeving only. This includes taking engine apart, installing custom sleeves, reconditioning pistons, and putting engine back together.
Now if there is a knock in engine means you crankshaft bearing goes caput, and officially there is no repair size bearing available, so you need new crankshaft.
Easier and cheaper to buy low mileage M278 from eBay and swap it.

9500 miles,

going to dealer next Thursday, see what they say, I might have a chance to get some reasonable person to help me out.

How did you hunt down the defective components and cap and coil values?