That's why you disconnect both ends. The blockage is typically on the intake side, near the end of the pipe, or actually in the intake. I've never been able to get a cable to go all the way through from the EGR side, there's a couple of 90 degree turns, so work from both ends, then blow it out with air pressure, some use a solvent. If it's blocked on the intake side you just dig it out as best you can with a hook, some use a drill bit. Those instrument pod pullers serve so many purposes. BTW there is an intermediary bracket on the rear of the pipe that has to be removed for good access to intake side.