Hello fellow Multimen/women.
My 07 multijet is driving me bonkers of late. Its got 80K on it and I get a repeated, intermittent engine warning light coming on. Using multiecuscan, I can determine that this is the EGR valve. or is it?? It can happen when idling in traffic or accelerating on the motorway. The alarm comes on as well as the engine management light and it then runs in safe mode. Strangely enough, if I turn the ignition off and restart the engine all is fine, no more safe mode, but the light remains on. But after a time (could be a hundred or five hundred miles) the light will no longer come on. Strange methinks.
I've taken the EGR off and cleaned it, in fact it was fairly new when I got the car to years ago having been replace by the previous owner. I've checked it whilst off with Multiecuscan and you can see it operating fine. Some times the error code tells me that there has been over boost pressure, as well as insufficient exhaust gas flow. So then, if the EGR is working fine, and this fault is intermittent, could it be a sensor fault, and if so which one?
Thanks for your help peeps.

If you get the engine warmed up by gentle driving, can you then provoke the beep and limp mode by flooring the throttle, in 4th gear, from just over tickover up to about 3,000rpm?

Yes I can, but not always as mostly it runs fine, but this is one way that it does come on. best if I am accelerating up hill , then it will hit 3K and the beep comes on! But sometimes it does it sat in traffic!!! I'm confused. com!

Check all the small bore vacuum hoses and connections to/from the boost solenoid that's mounted off the air filter tray and the little reservoir that's around the back of the engine. Look for any little knicks or splits. Might even be worth replacing it all with some silicon hose off ebay as it can be had quite cheaply and that won't perish.

That sounds a good step forward to me. 'Boost solenoid' ? what does it look like
Thanks.

So then, I've spent a couple of hours checking all the vacuum hoses. I see what you are getting at. That the vacuum may not be operating the turbo control unit properly. However I found that all the hoses seem to be in good order. The control solenoid on my car is just to the right of the air box on a bracket of its own. I found the red hose coming from it and followed it down to the turbo control, I think this is a diaphragm of sorts that operates a waste gate? am I right?
The black hose that comes from the same line that feeds the brake servo, goes to one side of the solenoid. If I disconnect that then I can feel lots of vacuum on it when the engine is running. So I take it, that all that goes before the valve must be ok? However If I suck on the end of the red hose the rod on the diaphragm unit does not really seem to move, although it is not easy to see, but if I then blow down the red hose the rod moves out, but only about four or five millimetres at best. How far should the rod move?
I got under the car and put some oil on the diaphragm rod and linkage, so I don't know it that will help. How can I check if the solenoid valve is working. Should it let vacuum past it when the engine is running or does this only happen when you accelerate?

Questions questions!

Yes, it's a bellows connected to the pushrod that you can see sprouting out of the pressed metal housing on the turbo. It's not operating a wastegate; the pushrod moves the variable geometry turbocharger (VGT) vanes that are housed inside the turbo, right next to the impeller on the exhaust side.

If you get someone to rev the engine, you should be able to see that rod moving. If it doesn't, you've either got a problem with the vacuum hoses, or the VGT mechanism is gummed up. It's a twiddly bit of kit that you wouldn't think has a hope in hell of working, but it does:

or at least it does when it's clean:

Thank you yet again for your help. I've just been reading another more recent post from a chap who has exactly the same problem. He suggests the vacuum hoses could be the wrong way round, and indeed mine seem to be, in that the red(small One) is at the front of the valve and the black one at the back. But I see that the plastic connections on the valve are, front small diameter and rear, large, So that would seem to say the red on at the front is correct, but I will change them around and see. However I still seem to think that the bellows bit is not moving enough. How simple is it to remove and clean without loosing the settings as I see there is a thumb screw adjustment on it.
Thanks again.