DPFE (differential pressure feedback EGR) sensor

[pnevesfoto]

DPFE (differential pressure feedback EGR) sensor

is it prone to die?
my W203 C220 CDI is starting to act up entering limp mode due to a P0401 code... valve working correctly but DTC cores keeps coming back to pending codes...

is the DPFE sensor expensive?
where is it located?
is it a DIY job or an expert reserved only job?

 

[cws196]

Have you had diagnostics via MB Star?

 

[pnevesfoto]

Have you had diagnostics via MB Star?

Yes, the first time it was P0402 read at my local indie (I believe he has STAR software, because he identified several DTC codes referring to climate control flap controller motors...
now I have an Autel Maxiscan MS509 and that is the one that I use to explore and delete error codes...
as you can see in this post on another thread, I've been battling this issue for some time now... :

I'm having the same DTC code... P0401... but my auto gearbox is perfect with no error nor malfunction...

When first started, I suspected MAF troubles... took it off, inspected, cleaned it and refitted... problem persisted...
Took off th EGR valve, cleaned it, refitted it due to a P0402 code read by STAR software at my local indie (this meant too much volume of exhaust gas recirculation - probably EGR stuck open temporarily and then working again)
All was right for about 800km and suddenly at the end of a 250km trip, it came up a fault code P0401 (now the recirculation is insufficient... what the f... !!!)
Took off the EGR cover and watched it at idle and in acceleration... seems to be working fine... opens and closes normally...
The fault came back 3 times more on the same day (yesterday), so today, I'm unplugging the EGR valve and let it run with the P0403 code it generates when unplugged, to see what happens...
I'm afraid it will clog the DPF a litle but it will be for a few hours and a few miles test only...
I start to suspect the DPFE (Differential Pressure Feedback EGR) sensor is gone... but I don't seem to find it on the engine bay so I can't test it...
Do you know where it is placed?
I know that it must read out 1,3~1,7VDC with a reference voltage of 5VDC, but I don't know where the plug is to measure the output voltage of the sensor...
The only one I find with the pipe coming from EGR system is the MAP (Manifold Absolute Pressure) sensor, which MB reference is A0041538428, at the front of the engine... I read somewhere that the DPFE would be at the back, behind air filter compartment ...
Can anyone help with his previous knowledge?