I reset the DTC by pressing the switch 8 seconds after each code is read. The code is still #5 and #21 consistently. Reading the posts, I knew the location of the EGR and it is above the exaust manifold. But where is the purge switchover valve (SOV). Researched in the MB shop manual, there is a exaust gas recirculation SOVs. Is it the same as purge SOV . Authur, if you read this message, could you provide me the procedures for testing the purge SOV valve for Code 21. Does fuse #7 being blown has anything to do with Code 21 or only a bad fuse. Fuse 7 provide power to EGR SOV and purge control valve. I will test the EGR valve as Authur suggested using the vacum pump.
Thanks in advance. I have use this forum to fix the idle problem as posted in the past.