No Engine Management Light

PeterW1966

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Hi All,

My first post here. I have done some extensive searches but apologies if I missed something already posted.

I bought a 2004 SLK 230 (R170) about a year ago. At the time (foolishly) I had not spotted that the engine management light was not coming on when the key was in the IGN position. Once I spotted this I checked for fault codes with a code reader and nothing was showing up. The car runs well with no obvious faults. I also pulled the connector off the MAF sensor (which I understood should trigger the engine warning light) - nothing.

Whilst I thought it was unlikely that the bulb had blown I bought a new bulb and today I went about changing it. The dash removal was surprisingly straight forward, which was a relief. However, I checked the engine management bulb and it looked fine. I replaced it with a new bulb and still no light with the key in IGN position.

Now here is something that worries me even more. I also changed the front discs and pads today. The pads were very worn, to the point where the wear sensors on both sides were clearly worn through (showing metal). However, I have not had a warning light come on for this. The brake wear warning light does come on with the key in IGN position (along with all warning lights apart from engine management light). They all go out once the engine is started.

So, I am trying to find out if there is some know "bodge" that a previous owner may have done to hide an engine management light triggering fault? Or is there a known issue that could effect all warning lights? I did try pulling the connector off the brake fluid reservoir and this didn't trigger a light, but maybe this is normal.

Any ideas or suggestions will be gratefully received.

Thanks
Peter
 

E55BOF

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Welcome to the forum.

Which code reader did you use? It may well be possible to code out the EML with a dedicated MB Star unit, but I suspect very few if any code readers would detect that. If I were you I'd have your codes read and settings, specifically the EML, checked by an indie with a Star as soon as possible.

If the wear sensors on the front pads are not connected to anything the brake wear circuit will not light up when you use the brakes, no matter how worn they are. Disconnecting a sensor and bridging the loom to complete it with a piece of wire or a paperclip will show whether this is the problem, but I can't see any way this very simple circuit could affect the EML.
 
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PeterW1966

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Welcome to the forum.

Which code reader did you use? It may well be possible to code out the EML with a dedicated MB Star unit, but I suspect very few if any code readers would detect that. If I were you I'd have your codes read and settings, specifically the EML, checked by an indie with a Star as soon as possible.

If the wear sensors on the front pads are not connected to anything the brake wear circuit will not light up when you use the brakes, no matter how worn they are. Disconnecting a sensor and bridging the loom to complete it with a piece of wire or a paperclip will show whether this is the problem, but I can't see any way this very simple circuit could affect the EML.
Hi E55BOF,

Many thanks for the reply.

I only have a generic (cheap) code reader. I was concerned that maybe this wouldn't pick up all MB codes. I will see if I can find a local garage with a Star tester. I did speak to a MB specialist a few months back and he was not aware of any way to disable the EML through Star.

The brake sensors are connected to the sockets on the caliper, but I couldn't say for sure that these are connected to anything. No obvious signs of tampering though. I will try a direct short to ground just to check.

Really, I just wanted to try to trigger one of the other warning lights on the dash to see if more than the EML has been disabled.

Thanks again for the reply.

Peter
 
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At least you’ve spotted it now - no EML on start up = MoT fail
 

markjay

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On another note.... does your car have the M271 engine? If so, then you want to ensure that the EML is working, because the EML might be the first sign of the impending doom that can result from premature timing gear failure.
 
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PeterW1966

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On another note.... does your car have the M271 engine? If so, then you want to ensure that the EML is working, because the EML might be the first sign of the impending doom that can result from premature timing gear failure.
Hi markjay,

How would I know what the engine type is? :)

It's a 2004 SLK 230 Kompressor with automatic gearbox. Does that help?

Thanks
Peter
 

markjay

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Hi markjay,

How would I know what the engine type is? :)

It's a 2004 SLK 230 Kompressor with automatic gearbox. Does that help?

Thanks
Peter

If it's the 4-cyl 1.8L Petrol engine with the Kompressor supercharger... than unfortunately yes it is the M271 engine.
 
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PeterW1966

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Is there a home diagnostic reader that would allow me to undo any software fiddle that a previous owner may have done?

I have seen options from CarSoft and iCarSoft which would probably work out not much more than a diagnosis / fix from a garage. Not sure if they are any good and if they can programme / activate features.

Anyone had any experience of these or other tools at home?

Many thanks.
 

markjay

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It's an SLK230, which is a 4-cyl 2.3L petrol. Did a bit of digging and the engine seems to be an M111.973.

Good news! No need to worry about the timing gear then :thumb:

(The M111 engine is actually the precursor of the M271, it's 2.0L Kompressor, but luckily does not suffer from the timing chain issue)
 

350_Coupe

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Is there a home diagnostic reader that would allow me to undo any software fiddle that a previous owner may have done?

I have seen options from CarSoft and iCarSoft which would probably work out not much more than a diagnosis / fix from a garage. Not sure if they are any good and if they can programme / activate features.

Anyone had any experience of these or other tools at home?

Many thanks.

I wouldn't want to bet on it, Mercs tend to be a bit temperamental like that and a STARS setup is usually required before going and messing around with stuff, but more importantly, a knowledge of what you're messing with is equally as important.

It would be a touch worrying if there were a way to disable these warnings! I'd take it somewhere trusted to give it the once over.
 
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PeterW1966

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I wouldn't want to bet on it, Mercs tend to be a bit temperamental like that and a STARS setup is usually required before going and messing around with stuff, but more importantly, a knowledge of what you're messing with is equally as important.

It would be a touch worrying if there were a way to disable these warnings! I'd take it somewhere trusted to give it the once over.
Agreed...very worrying if it can be done. I'd also be surprised that Google doesn't throw anything up on how to do it, if it is possible.

I think that the MOT failure has only come in in the last couple of years, so presumably someone would have just removed the bulb in the past.

I'll bite the bullet and get a specialist to take a look. Anyone have any recommendations in the West Sussex / Surrey area?

Thanks
Peter
 

350_Coupe

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I'll bite the bullet and get a specialist to take a look. Anyone have any recommendations in the West Sussex / Surrey area?

Thanks
Peter

Travel an hour north and visit @richard and @Alfie at COMAND located in Lightwater, not sure i'd trust anyone else as much with this kind of work to be honest, knowledge and experience is key
 

pmcgsmurf

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You said it yourself about the dash, fairly simple to get out.
Sadly it is failry simple to do a mod. to the dash to stop the supply to the lights.
 

E55BOF

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Sadly it is failry simple to do a mod. to the dash to stop the supply to the lights.
All the other warning lights work as expected, though, so the power supply seems unlikely to be the culprit.

STAR will find out what's going on; I don't think an iCarsoft, or equivalent, will.
 

pmcgsmurf

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All the other warning lights work as expected, though, so the power supply seems unlikely to be the culprit.

STAR will find out what's going on; I don't think an iCarsoft, or equivalent, will.

I mean each light, all you have to do is cut the track.
 

E55BOF

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I see what you mean. Pretty drastic bodge, though, if the EML can be coded out, because not easily reversed - the dash would have to come apart again.

OP, get a Star diagnosis. That should tell you what's going on.
 

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