e420 "check engine electronics" / misfire?

I just got a message of "check engine electronics" on my '97 e420 sport and it appears to have a misfire. I recently changed the oil tubes due to a lost plug in one of them and a lifter noise. The lifter noise went away and it ran fine. Then my wife told me about the message tonight and I checked to see if one of the coil plugs had come loose or maybe I just did not get it back on all the way, but they were all tight and looked good. Any suggestions? Do I need a scanner to get the codes, or are ther any basic things to check first?
 
Any help is greatly appreciated!
 
Thanks,
Tewlmn