Hi Dunk,
Its in the thermostat housing, it usually well stuck into the housing and will not come out. Best bet is fit a new Febi pattern part (Complete stat and housing assembly) as it contains a new sensor already fitted. You may be lucky and it comes out when you remove the retainer circlip – but I very much doubt it!
All the best
Steve

Steve, I was able to have the codes read and have two active codes p1470-8 Charge pressure control has open or short circuit and p1403-4 EGR cable short circuit. There was also a stored p0600-4 Databus faulty. What are the expected values on the wires 1,2,and 3 leading to the EGR?

Hi Kevin
If its a 3 wire EGR then MB colour codes should be:

Red – +12v
Brown – 0v
Grey/yellow – PWM

Engine on idle, PWM 3.5V (ish), +12V 14.00-14.50V Bare in mind that its pulsed voltage on the PWM and its difficult to read accurately without a scope but at least you can check supply and ground.

Its more likely to be the cables to charge pressure control valve broken as these run across the front of the intercooler.

I hope I have understood you correctly and have in mind the correct model.

Regards Steve

Thanks it is a 3 wire. I assume if supply and ground check out I may need a new EGR. Any way to test by applying voltage to the PWM and looking for movement?

Hi there, If you remove the unit from its location in the manifold circuit and turn the ignition on without starting the engine, you should see the valve move between its stops as part of the system self test/calibration routine. I hope this helps.
All the best Steve

Thanks. I removed the EGR by unbolting it from the manifold but kept the wire harness in place. Had my son turn the key to run. Lights came up on the dash but no movement at the EGR. Tried again with keeping the EGR grounded to the manifold. Still nothing. Started the van and revved to 2500 rpm. No EGR movement. Physically worked the mechanism after removing the little black plastic cover. The valve opened smoothly and easily. Can I run power to the EGR to verify that it is bad? If so +12volts supply, -ground, and then another +12volts to the control wire?

Ok Kevin, in my book looks to be faulty. However there is really no way to test the valve by applying voltages to the pins, its a servo motor and some electronic wizardry in there and can be damaged by just ‘bobbing’ voltage on. The signal changes are so small between open and closed that the only way to actuate the valve in a test mode would be using the Mercedes star diagnostic tool, or at least some thing similar.
All the best
Steve

Your help is really confidence inspiring. Got a new EGR from europarts for $600 and plugged it in. I again cycle the key to run expecting a test cycle but there was no movement. Is it possible that the ECU will not test the new EGR until it is reset. If so is there anyway I can induce the ECU to reset or does this need to be done at the dealership? I did disconnect the ECU harness connectors and then reinstall it but there was no change. Thanks Kevin

Hi Kevin,
I am unsure if the limp home condition actually disables the EGR circuit or not. Did you compare simple resistance measurements pin to pin from the old to the new valve? Did anything look/test unusual?
Its so difficult to fault find by email as its always a ‘best guess’ situation and I do hope we are going in the right direction! I have a Vito outside 2008 model (similar engine controls configuration) that when you turn the key off from running you can hear the EGR cycle. Its like a high pitched electronic hum/buzz that lasts for a couple of seconds after the engine stops. I have always understood and known this to be a self-cleaning cycle and is not uncommon on other makes of vehicle too – Ford Transit is another one that sings on ‘key-off’. The same noise usually occurs on Key on with engine not running (here is an instance where it is confirmed the Sprinter EGR makes a noise when turning the ignition on: http://sprinter-source.com/forum/showthread.php?t=35375 ) You are obviously not seeing/hearing this, therefore I am assuming there is still an issue or associated problem here.
Here is a little general background reading on the function of the EGR and its control you may find informative or at the very least interesting (it makes reference to petrol engines but the working principals are the same): http://www.aces.edu/~parmega/efi/egr.txt it could help you out.
Did you try the vehicle on the road – is boost back or is it still in Limp home?
If you re-read the codes from clearing them, what codes remain. Maybe another clear down and read would tell you what you have rectified (or not) so far.
I know it can be frustrating with these type of faults but a little reading without searching too hard will indicate many others with similar Limp Home problems that take forever to track down and lead back to different causes in many cases. I hope you are not too disheartened!
All the best
Steve