Hi Folks,

I have been hitting my head against the wall trying to fix Code 5 on my 95 E320 W124 wagon. I have seen plenty of discussions on the EGR issue with W124s so I am hoping folks here can point me in the right direction. I have been chasing down everything I can find on the forums and it has not gotten me anywhere.

My observations thus-far:
-EGR itself works fine. Pops when vacuum applied, snaps back when vacuum is removed. I cleaned the EGR tube anyway and also replaced the gasket at the throttle body side.
-I have steady vacuum going into the EGR SOV, but no vacuum coming out.
-I just installed a new SOV (new from MB), but still no luck.
-I cleaned the corrosion off the electrical leads and confirmed I am getting voltage at the leads. The EGR side was about 12V the smog pump side was around -13.5V if I recall correctly.
-Here is where it gets weird. After I cleaned the leads and reinstalled, I had vacuum at the SOV to EGR outlet. Two days later, the CEL came back on and I am throwing code 5 again. I checked the SOV and now there is no vacuum. I don't know if the dielectric grease I put on the leads could be part of the problem, but I figured I'd include that detail.


This problem has been driving me up the wall. I love this car and want it to be running perfectly. My mechanic told me the EGR is quite likely the cause of my rough idle. If anyone can help me figure out what I am missing I would be eternally grateful.