# repair or replace ecu for mercedes



## markowitzman (30 Aug 2007)

Main dealer tells me that ecu needs replacement. Does anyone know someone in ireland to repair an ecu or assess same?


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## xt40 (31 Aug 2007)

what kind of problems are you having. if your unsure if it needs replacing or not, i presume the car is still going.  a couple of years ago, i had a wiring short which caused my ecu to start smoking and stop working .the dealer said i needed a new one but before shelling out, i cracked it open to have a look. a 2p resistor from peats and a bit of solder later and the car is still going today.


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## Caveat (31 Aug 2007)

Whatever happens don't even think about a _new_ ECU - I shudder to think how much this might cost for a Merc - €1000 + ??  

Worst case scenario, 2nd hand should be easily enough available for about €150, then maybe same again to fit/check.


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## markowitzman (31 Aug 2007)

Thanks for advice.
Symptoms are as follows:
The car starts from cold in the morning but once warmed up it is virtually impossible to restart. Sometimes I have to leave it for 10-15 mins and then retry which is kind of awkward after filling up at the petrol station!
I sometimes have found that air con being on makes it more difficult to restart.
I am asking similar qs on merc owners website which is interesting also.
http://forums.mercedesclub.org.uk/showthread.php?p=201976&posted=1#post201976
they are recommending repair and/or second opinion?


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## markowitzman (31 Aug 2007)

cost is 1500 odd!


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## markowitzman (31 Aug 2007)

> Worst case scenario, 2nd hand should be easily enough available for about €150, then maybe same again to fit/check.


where is best place to get 2nd hand one and would any garage fit it?
Interestingly on the mercedes thread they reckon it may not be the ecu at all bearing in mind the symptoms and they are stressing a second opinion.
I thought once car put on diagnostics that problem should be "diagnosed" with ease and it would be cut and dried?


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## Caveat (31 Aug 2007)

markowitzman said:


> where is best place to get 2nd hand one and would any garage fit it?
> Interestingly on the mercedes thread they reckon it may not be the ecu at all bearing in mind the symptoms and they are stressing a second opinion.
> I thought once car put on diagnostics that problem should be "diagnosed" with ease and it would be cut and dried?


 
Problem is though, as I understand it, it's the ECU that diagnoses faults - not sure if it can diagnose that it, itself, is faulty - if you know what I mean.

Try Traynor's breakers in Co Tyrone for 2nd hand ECU - might want a Merc dealer to fit it though.


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## markowitzman (31 Aug 2007)

this most accurately describes the problem as reported by deskbound on this link
http://forums.mercedesclub.org.uk/showthread.php?t=29610&highlight=ecu


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## Caveat (31 Aug 2007)

Sorry - can't really help specifically.  

My only experience with ECU failure was with an old Fiesta.  It was a well known problem with the model & I had mine replaced *three* times, but luckily on each occasion I managed to get a 2nd hand replacement - about €90 + about €120 to fit/test.

Don't know the anatomy of your Merc - the fitting cost is basically labour, but if the ECU in your Merc is located in an awkward position, it might cost a bit.  Also, 2nd hand Merc ECUs may not be as commonly available as Fiesta ECUs.

Good luck with it anyway!


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## ford jedi (1 Sep 2007)

what year and what model have you got? have the main dealer diagnosed which side of the ecu is at fault ,ie no fuel pressure /no crank signal as there are alot of other items which can cause a no start when the car is hot,is just a lot of these faults are missdiagnosed


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## markowitzman (1 Sep 2007)

00 E270 CDI
No Fordjedi no mention of exact problem.


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## ford jedi (1 Sep 2007)

well that narrows your problem alot .alot of cdi engines suffer from injector failure when they are hot more so than cold,this in turn shuts down the high pressure fuel pump, giving you the no start situation .which leaves you crankin the engine over for hours and nearly flatenning the battery,.most common problem with common rail engines is alot of people dont have the equipment to test fuel system,s properly.my guesss is you have an injector or two over fueling,
this can be easily diagnosed .i would defo not go for an ecu yet


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## markowitzman (1 Sep 2007)

thanks for that. so ecu coming in on monday to main dealer. should i ask them to check for injector failure instead. I would worry about how I would stand if they fit ecu and still no improvement?


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## ford jedi (1 Sep 2007)

hopefully it will be  ok,but i doubt it havent seen that fault on too many mercs,cdi,s which main dealer is doin it just out of curiousty? 
jon


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## markowitzman (1 Sep 2007)

hastings westport co mayo


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## markowitzman (9 Sep 2007)

had a second diagnostic done with an independent company and they say fault is ignition switch and that ecu are ok. Is this more what should be expected? thank you.
[broken link removed]​


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## ian888 (22 Apr 2009)

http://ecutesting.com/mercedes_a_class_ecu_and_air_f.html

If you buy a second hand one, the unit needs to be coded for your car.
These people will repair your ECU and guarantee it for 2 years at a reasonable cost.


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