multiple codes , one causing the other?

[redlobster]

I have a CEL on and i pulled the codes today, here they are

03 02 - EGR Hi/Low Flow

03 04 - Knock Sensor

04 01 - Front Right Heated O2 Sensor

could one be causing the other to go off etc? Should I go ahead and replace the

o2 sensor and the KS and attempt to clean the EGR tube Ive been reading some about?I got two bolts off of what I thought was it after I took the IAC off but I couldnt figure out how to unbolt the rest of it, really wasnt sure what I was reaching/looking for. Im leaving for the Air Force soon and want to have the vehicle for the most part ready for my wife without exsisting problems, till I can get back to fix something.

its a 96 Max GLE

[Beancooker]

I'd start by cleaning the EGR valve, and trying to get that working. It could be what is causing the o2 sensor to throw codes.