Stopped to get gas and car was running beautifully. When I got back in the car I got zero response from pushing the push start, got a “remove key” message when I tried to actually start by using the key to turn it over, and all I can get as far as a response is a very faint click type sound from inside the dash when I push the the start button. No gauge or instrument lights whatsoever during everything. I can however access and use command at all times regardless of trying to start the car. Charged battery, tried jump start, as well as jump box with no change or difference. Really trying to avoid towing it to the dealership unless absolutely necessary and will take care of whoever gives me the tip that gets my car started and avoid the trip to the dealership. That’s a working solution I’ll be able to accomplish myself, not sure if it’s as simple as that but I’m crossing my fingers. Car is a 2010 E550 coupe. Anyone else have this issue? Happened out of nowhere.


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Be sure to first diagnose not throw random parts at the car.

Measure battery voltage at the battery , it needs to be above 11.7 V , 12.66 is a full charge.

Next measure battery voltage while trying to crank.

Next measure voltage at a junction block / fuse panel.

I'd need to see a wiring diagram to go any farther. ( There might be a main relay or main power wire problem. )

Got a full charge on the battery and put it back in and forgot to mention a probably important message it displays when trying to start. It says key not detected followed by replace key battery when I use the pushstart and then displays remove key when I try and insert it to turn it over. I’ve tried two different batteries so I’m doubting it’s a bad key fob battery issue. The key still is recognized because it unlocks the doors automatically and I can turn on the command unit and enter engineering mode/control stereo/etc. I haven’t checked the voltage on the battery during my start up attempts because it honestly doesn’t seem as if it even makes it past the first component as far electrical ignition functions go. An unrecognized key would make sense in this scenario being the car wouldn’t even begin to turn over if the key wasn’t present but curious as to how it would out of the blue randomly quit working and how the other functions of the vehicle would continue to recognize the key. Has anyone ever problems with a key needing reprogramming randomly?


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Thank you for the response by the way. Not kidding when I say I’ll kindly compensate you if you can save me a trip to the dealership.


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Does a different key operate the car normally? If so, that would point to a failed electronic section of the key in question.

How bright are your headlights? Do they dim significantly when you try to start the engine? A crap battery or poor connection can cause all sorts of weird problems, especially with the high current draw of the starter motor.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I'm not familiar with the " Keyless Go " system on this car. I'd expect if the doors automatically unlock on approach / handle pull, that should be enough authorization to crank / run the engine when the start button is pressed.

You still need to check voltage starting at the battery and various branches. It is possible that a branch has a bad connection causing the problem. Be sure to check for voltage while trying to crank as voltage can be good without a load then drop dramatically with a load.

Having a wiring diagram is a vital next step.

No, the same key is used to access everything and start the car. Headlights are normal. Nothing skips a beat when I try to start the car. Radio will play constantly regardless of how many times I try and start the car. The no key detected message is what’s throwing me for a loop. I can check for voltage while I’m pressing the push start button but I really don’t think it will affect at the battery end of things being it’s acting basically like you didn’t even have a key and sat down and tried to start it. That’s probably the most accurate description I can come up with. I was thinking maybe a relay at first because the process doesn’t even seem to make it to first base but with it not detecting a key in the first place makes me think of several possibilities that I’m at a loss of how to diagnose let alone solve on my own. Here is another question for my fellow mercedes enthusiasts.....I read that the Mercedes Benz Roadside Assistance service lasts for the duration of the car regardless of ownership which I thought was unbelievably incredible. I know they’ll send out a certified/qualified service tech to handle the call but my question is will this tech be able to diagnose the issue at hand, and then tow the car to the dealership if necessary? Or is it strictly a help change your tire/check your fluids kind of tech that facilitates a tow if necessary?


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You will need to take this to a shop, not being able to diagnose leads to randomly changing parts.

This was changed some years ago. The car owner must have spent X amount within Y days at a dealer for it to be valid.

That's not what I asked. I asked if you tried a DIFFERENT key. Cars come from the factory with 2 sets, have you tried the other one to see if it does the same thing? If it does, the problem is with the car somewhere, if it doesn't, it's with the key you've been using.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

It may have originally came with two sets but sadly only one of the set made it into my hands when I purchased the vehicle. If I had another key I’d be able to eliminate that probability pretty quickly. Guess I need to suck it up and have it towed to the dealership. Anyone know if the Mercedes roadside assistance will cover the towing? It’s atleast a 50 min drive to the dealership.


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Ahhhhh....damn. Makes sense from their perspective but at least it sounded good in theory. I’ll suck it up and get it towed. Thank you for the help though. Definitely appreciated.


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Please post the outcome to help others.

If the repairs are completed at the dealership the towing should be free


Mercedes-Benz Roadside Assistance - Eligibility and Coverage

__________________
Paul

They changed the roadside assistance some years back. It’s free if you have some minimum spend with the dealer shop, otherwise there’s a fee. They’ll let you know.

__________________
Prost!

Absolutely.


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