Dan T

Hello everyone.
I am not very knowledgeable in cars and engines so bear with me while I try to explain my problem.

I have a petrol C200K Coupe from 2003 that I drive occasionally, once or twice a week for shopping or nearby business. Today I left for a longer trip than usual and after I passed a series of speedbumps (which I tackle carefully in this rigid suspension car) suddenly the car makes a series of honking noises (I thought that some other car alarm nearby went off or something) then I notice I can't accelerate anymore so after 100-200 meters I stopped. Check engine light, ESP warning light, SRS warning light, parking brake light came on and maybe others I can't remember. Tried restarting the engine but after a few revs it stops. Ok I guess its time to call roadside assistance to get me to a service. While I'm talking to the guys at the call center I try starting it a couple more times and I give up and wait for them to call me a tow truck. Some 15 minutes later they call back to tell me they sent someone and while I'm talking to them I try to start again and ITS A MIRACLE the car starts like nothing happened, also sometimes during all of this while I was pushing the buttons on the instrument cluster I see a brake light warning. I was able to take it back home without any issues. I made a service appointment for one week from now at the authorized local dealer (I don't take it anywhere else) but I'm really curious about what could have caused such an episode. Car didn't give any signs of trouble except a license plate light warning I had on and off for some time, but the lights there are working so I put it off for when I have some free time to change the bulb.

So what do you guys think could be the problem?

Thanks for your time and patience.

C230 Sport Coup

Well, likely electrical.
Read the codes, and post them here.
Not sure how to read the codes?
Well you only need a cheap BT OBD dongle and then download
Torque to your smartphone. Or local auto parts store, ask around.

Check the voltage on your battery.

Could be anything.
Something loose, (since it happened on a bump) hopefully codes will pinpoint.
#1 rule of cars. Always go back to the last thing you did.
What was the last repair performed on your car?
Any alternator or starter repairs?

Also could be fuel pump on it's way out.
Mine went sort of gradually until it died completely at ~220K Miles.
That won't throw any codes typically, but you can easily check the fuel pressure off the
front of the engine, on the fuel rail. Easy to get to, screw on the guage, and
fire it up. If it's not at ~50 + lbs of pressure, its on it's way.
Some auto parts stores here in the states will loan this for free,
C200 guessing you are in Europe.
Bought mine at harbor freight for $20.

My 2002 C230, M111 the camshaft sensor on top of the valve cover, something I'd never touched,
came loose once, the car stopped immediately.
Ran the codes, told me right away cam sensor issue, plugged in the connector (dealers broke the tabs arrgh)
put some tape on it, and no issues since. I check it every time I open the hood.

Check the voltage on your battery, read the codes and reply back, and what repair was performed last.

Dan T

Really appreciate the info. I'll order one OBD Dongle, unfortunately I won't be able to use it as I'm leaving on a work trip til next Monday, when I'm taking the car into the shop anyway.
Can you tell me if this https://www.ecutool.com/Super-Mini-E...ool_10677.html is a good choice?

The very last thing that was done on the car was one control arm (front right) replaced. Along with that the yearly service A, oil change, filters etc. and they said there were no other problems. This was in August.
A little before that I had both lower beam xenon bulbs replaced (one was dead) and while I did that I a neighbor checked the battery and fuses and it was all good, but that may have changed.
Alternator pulley was replaced 2 years ago, and the battery is 3,5 - 4 years old, so.... come to think of it, it may just as well be the battery.
I'll see if I can check it tomorrow again before I leave if not I guess I'll find out on Monday when I get back. I'll be sure to check back and tell you what it was.

Thank you very much again for your time.

C230 Sport Coup

Looks like the one I have. Come in pretty damn handy, and torque is kinda fun, assuming you have Android.
You can set up guages, do 0-60 times, etc . 1/8 mile time. Clear codes, I sprung for the $5 full version.
5 whole dollars....wow. Even better is the iCarsoft for Mercedes, reads Mercedes codes.
Regular OBD only tells you so much, but better than nothing.

I imagine there are equiv apps for Apple, but I dunno.
I'm not an apple weenie.

Anyway, codes 1st , see if that gives you a clue.
Than start looking for loose wires. Since you mentioned alternator pulley (why would anyone need to replace that?)
Maybe the bolt that holds the wires there is loose? Or on the starter.

Actually clean the battery contacts 1st....could be just that, if there is a marginal connection
due to corrosion.
And or if the wire that connects to the battery has wicked lots of crud into it, that causes some interesting problems.

Dan T

Thank you C230.
Still haven't got to ordering the reader (was eyeing some presents from that site as well for xmas and might as well just order them all at once) but I did take the car into the shop today.
Seems it was the alarm system after all that misjudged the situation and cut the fuel flow. Since it was not a MB installed alarm system and they didn't know about it I just told them to disconnect it for now.
I keep the car in the garage most of the time and everywhere I go its basically one security cam on top of another security cam and its not quite a car that would go unnoticed if stolen, colour being a pearly champagne. Not sure if its worth the trouble either.

Thanks again for your help, I may post codes if I find any when the reader arrives and if you're still interested.

C230 Sport Coup

Woa, An alarm system that cuts the fuel flow? Kinda stupid since you can't do squat without the key, since it has to turn
on the computer to allow anything to happen.
Only way to steal these cars is with a tow truck.

Dan T

The key can be cloned apparently. Most key copying shops around here have all brands of car keys just ready to be duplicated.
I used to have a Golf VI company car that came with the most draconian alarm system ever invented, where you had both a radio FOB, the key and a coded panel that you would have to enter a code every time you entered the car or the engine start again and thats the car they tried to steal 2 times lol, they actually managed to leave with it the second time around but they only made it a few blocks before the alarm figured out the car is being stolen and it stopped. Luckily I don't live in that city anymore.
So I guess that's what happened to me now. Unfortunately for the wrong reason. One of those speedbumps must've triggered it. Then, after 15 minutes, it just deactivated itself or recognized my radio FOB and it was like nothing happened.