First of all, change your garage. They are expensive and hopeless incompetents. Fault finding by swapping componenets is a sign of utter stupidity and a contempt for the customer wallet.

Was it running well with full power?

I would suspect some item not covered by the multitude of sensors***.. eg EGR valve clogged, catalyst clogged, exhaust broken and jammed.

*** I assume they did check all fault codes? By the list of changes.. I doubt it...

I have assumed that fuel is getting to the engine .. which is the usual cause of non starting.. but the glowplug relay could have failed... Or a failed off switch which does not switch on properly. and hence the fuel supply is not switching on properly.

EGR valve is remove and check. After 140k miles, bound to be clogged up.

Switches can be checked electrically. Catalyst is remove and check job so leave till last?

You really need a garage which knows what they are doing...

Edited by madf on 16/10/2012 at 10:46

Following on from Madf's correct post...incompetence and waste of incredible proportions by that garage...cars like this are best diagnosed and examined by make specific indy's, MB (and BMW) has a good spattering of very knowledgeable specialist indy's dotted about the country.

They are best found by consulting one of the good independent MB owners forums, you'll soon find out where to take the car for expert time served diagnoses from people who don't just fit new parts till they happen upon the cure by elimination.

My own MB indy usually can go straight to the problem with an accurate description of the symptoms, but that comes from being an MB indy for some 40 years.

A faulty EGR valve can jam open causing exhaust gases to recurculate stright into the inlet manifold and can make a car impossible to start.

That said it sounds like the garage is imcompetent and just guessing ! fault code reading is an art and you need a good brain to go with it !

It needs to be in a non start mode then start the diagnostics. very prone to injector issues leaking pressure ,causing low rail pressure causing intermitant and non starting !

Thanks for the info. I see people bypassing these EGR but im a believer that car should stay the way it was designed plus its not just a matter of blocking them as some people suggest. I will look into getting Rail pressure checked i must say car is starting better now but the intermittant limp mode is problem.

Thanks for all the advice

" I don't see how a sticking EGR would cause a non-start "

Best talk to the AA & RAC then, we get plenty of non starts with EGR valves stuck wide open !

If you are getting intermitant limp mode you may have an issue with the butterfly flaps in the manifold. Linkage falls apart.