Audi B7 2.0 TDI EGR electrical connector testing

[RyanBudden]

Hi all - So after going into limp mode, I got the usual EGR error code (P0403), so removed and cleaned the valve and reset the code, ran the exhaust test etc. The car ran great for a while, but then same error again ad this time with P1408 (although this one cleared and stayed cleared).

I checked the EGR valve and it was still clean, but when running the diagnostic, when the VAG tries to open the EGR valve, there is no response from the valve (VAG tries 40%, Valve feedback remains on 0%). there is no audible click either, so I don't believe it is opening at all (i.e. not just a feedback fault),

So I checked the electrical connector block that plugs into the EGR valve. It has 6 ports, one of which is not used. (i.e. only 5 wires). I tested them with the ignition on and engine running. The results are as follows, looking at the plug with the blank port at the Top right:

Ignition on
Top left - 12V, Top Middle - 12V
Bottom left - 0V, Bottom Middle - 0V, Bottom right - 5V

Engine Running
Top left - 14V, Top Middle - 14V
Bottom left - 0V, Bottom Middle - 0V, Bottom right - 5V

I then ran the exhaust test with the VAG and when it signalled the EGR to open, nothing noticeable changed on any ports.

Can anyone tell me what is supposed to change and what might be wrong?? Is it possible I damaged the wiring when removing the valve? This is driving me nuts....

[RyanBudden]

Oh I had the plug disconnected for the readings. Might make a difference. It's not really possible to check plugged in without stripping wires.

[RyanBudden]

Ok in case anyone else is having the same issues, when I checked my plugs, the clips were broken. I didn't think it mattered at the time, but I have now replaced them and the problem seems to have cleared. I think what happens is that it must heat up on long trips and with the expansion they probably vibrate loose and cause a poor connection.