My 1997 E300 Diesel (125,000 miles) has started throwing 2 codes with regards to the EGR valve. It started just after I replaced all the Injector return hoses due to B100 leakage with Viton hoses. I have replaced all the vaccum lines as well due to heat and age. There were no codes prior to this.
I have checked out all the hoses and wiring and can not figure out why this has happened.
The only thing I can think of is the valve under the injector cover might have a vaccum leak as the hard hoses were loose fitting when I put them back on.
Any Suggestions?
Thanks in Advance.

P.S. I run B100 home brew in both this car and my 03 Duramax with no problems and love it.