W203 engine cuts out and ignition lights come on

[MervC]

Hi,
My beloved W230 (2005) has recently started showing signs of problems:
About once a week, whilst driving at any speed, all of the ignition lights came on, the engine briefly cut out, and then within a second the lights went out and the engine kicked back in, almost as if nothing had happened.
I checked the battery connections (new battery about 6 months ago) and connections to ground and they seem fine.
This morning something similar happened but when the engine kicked back in there was very little power with the engine revving like crazy. I pulled over and switched off. After 5 minutes I started up again and made the last 5 miles to work without any issues (not sure about making the 40 miles home this evening, though!).
Has anyone experienced anything similar, please? It's sad to think that the value of my car now is making me consider changing it because if it's a major electrical fault it probably isn't worth spending too much on her but I am kind of attached to the old thing.
Thanks for reading this and for any advice you might be able to offer

 

[grober]

Could be several things. Abrupt engine/electrical failure can be caused by several things.
1. failure in voltage supply --- bad connection/ bad earth 2. a short to ground causing a big enough current drain to earth to drop voltage to critical levels.
Some things to check:-
The engine earth strap
the main fuseable links
the crank position sensor

Other possibility is the electrical fuel pump in the tank that feeds the main diesel injection pump [ accessed from under the rear sear IRRC]-if it fails to provide an adequate supply pressure the engine may shut down .
Having said that- First off get the fault codes read on MB star preferably- that should point you in the right direction.

 

[optimusprime]

Some MB have this stop thing if the battery is to low of charge. I know its new battery but charge it up and do a voltage check on it first ..Also check the fuses along with all earth points .But it could be the sam modual.

 

[Stratman]

Are there any faults stored in the OBD2 system?

 

[MervC]

Thank you all for replying, especially grober
My Mercedes is with a local garage who are testing all of the things mentioned (it's nice to be armed with some ideas!) and, hopefully, it will be a loose connection and not cost me an arm and a leg.
The replies gave me some reassurance that it might not be a completely screwed electrical system so thanks for that and fingers crossed!
I will post an update when I get news and am really hoping that is it a simple and not too expensive fix because my 12 year old Merc is a dream to drive and I really don't want to have to let her go for a newer model

 

[optimusprime]

Wish you luck .

 

[MervC]

So, I got my car back this afternoon after the garage checked all of the things that were suggested here (thanks again) and they could find nothing wrong. The told me that there were no errors reported when they used their electronic diagnosis tools and drove my car both days with no incidents.
The good news is that they didn't charge me so it just cost me a tenner in a tip for a drink for the mechanic.
The bad news is that I an no wiser and now wondering whether I have to bite the bullet and get a Mercedes Benz garage involved (and raid the piggy bank)...
Does anyone think that the diagnosis tools used by Mercedes Benz will find more than whatever my garage used? Perhaps MB deliberately hold back error messages if their own testing equipment is not used.
I am not sure what to do now but am cautious about just carrying on with my car as it is, in the hope that the problem does not happen again, because I am on the motorway 5 days a week.
Thanks again for your advice and, on a brighter note...
Enjoy the long weekend! :bannana:

 

[ampwhu]

i think the main dealers use the same computers as the Mercedes militants.

mixed opinions on this.

 

[LvR]

Given what has been reported as symptoms and investigative results at this stage, I would be inclined to suspect something power/battery/earth/relay related ................. STAR is not necessarily going to be able to pick up such an issue because eg the ignition power disappearing is considered an "allowable" occurrence on the vehicle because the operator could have turned the power off via the ignition switch.............

That said, I would anyway start with a STAR scan and see what if anything is brought up that can be investigated.

and then within a second the lights went out and the engine kicked back in

Critical this .............. is this iow a manual boxed vehicle?

If yes see above....................... if no I think you need to give a lot more info as to what else is happening at that time and what you experience ito mechanical feel and noises

 

[MervC]

Thanks ampqhu and LvR
The mechanic did say that he removed and refitted the battery and earth connections so maybe that has fixed it? I took her for a run this morning and there was no sign of the problem but I probably won't feel confident about driving it long distances again until it doesn't happen for a few weeks.
LvR asked: is this iow a manual boxed vehicle?
It's an automatic gearbox. As for more info: There were no mechanical noises when the engine cut out and for less than a second there was power loss but when the engine fired again (without me doing anything), power picked up again immediately every time until the last incident when the engine did not fire again and I had to pull over.
I think that I will just have to run it around over the bank holiday weekend and see what happens - My 2 nearest MB garages said that they can;t look at it until next week so I don't have much choice at the moment.
Thanks again to everyone who commented and has tried to help. I will give an update when something happens or doesn't (hopefully)

 

[LvR]

LvR asked: is this iow a manual boxed vehicle?
It's an automatic gearbox. As for more info: There were no mechanical noises when the engine cut out and for less than a second there was power loss but when the engine fired again (without me doing anything), power picked up again immediately every time until the last incident when the engine did not fire again and I had to pull over.

THAT is strange ..................... and imo should not be able to happen on an auto at all. I am not claiming to know it all, but with an auto there is nothing driving the dead engine (what you experienced?) to restart it mechanically and electrically that can only happen if you have some sort of echo green fuel saving device/mode that has a headache

 

[MervC]

THAT is strange ..................... and imo should not be able to happen on an auto at all. I am not claiming to know it all, but with an auto there is nothing driving the dead engine (what you experienced?) to restart it mechanically and electrically that can only happen if you have some sort of echo green fuel saving device/mode that has a headache

It's all a mystery to me, if I am honest - I know nothing about cars and do appreciate you taking the time to give your opinion and insight.
I will see how it goes and keep an eye out for a new model because it is probably getting to the point where what I spend at a MB garage won't be worth it on this car, sadly. Maybe it was a loose connection and it won't happen again but in my experience, when you start to lose confidence in a car getting from A to B and there is no obvious fault that can be fixed, the joy of a car you loved driving fades pretty quickly.
Thanks again!

 

[Stratman]

Is it possible the torque convertor lockup was engaged and this is what was driving the engine?

 

[LvR]

Is it possible the torque convertor lockup was engaged and this is what was driving the engine?

Sure is ............................but then it was said also

whilst driving at any speed, all of the ignition lights came on, the engine briefly cut out, and then within a second the lights went out and the engine kicked back in, almost as if nothing had happened............................................morning something similar happened but when the engine kicked back in there was very little power with the engine revving like crazy.

So if the tc is locked there is no way to have a free revving motor with no power.

I suspect we don’t have the full story/picture here

Just for the record - I have never ever tried to bump-start a diesel like this ...................let alone an auto diesel like this............ and I will never willingly do, so I may be misinterpreting and comparing with experiences in way older vehicles in order to comment

 

[Old spanners]

Could this be your problem?
https://www.youtube.com/watch?v=uQP8gu_HVd0&t=85s
I have seen a lot of problems related to the alternator voltage regulator and brushes on various forums and videos.

 

[en_vogue]

@MervC did you ever get this sorted? I have the exact same symptoms inc it restarting itself. Sorry to dig up an old thread!

 

[grober]

With modern cars it's almost always electrical. Check the battery [ age] alternator, engine earth strap, main fuse links, fuse box and any other unit likely to drag down the operating voltage. You could try rigging up a voltmeter to monitor the voltage constantly so you can monitor any dip in the 12 Volt supply when the fault occurs. Better still take it to a good vehicle electrician.

 

[CIGB]

@MervC did you ever get this sorted? I have the exact same symptoms inc it restarting itself. Sorry to dig up an old thread!

sorry to bother you , did you get this problem sorted, my 200 cdi auto is doing exactly the same, cuts out and restarts itself while driving, and if at night with lights on auto they go out as well

 

[mipsten]

Hey guys, did any of you figure it out? Same symptoms here on a CLC 200 CDI automatic

 

[gogolilov]

Has anyone found what the problem is? I am experiencing exactly the same for the past two years.
No errors saved, the car is running perfectly fine and just restarts.

It is 2009 CLC 220 CDI