I never actually found an appropriate wrench for the lower nut (pipe fitting) for the EGR tube. The bottom nut atop the pipe fitting is somewhere around 21mm-22mm. They're a bugger to separate; I'd soak them in PB overnight.My '01 sable with 125k keeps throwing the P0401 code. I replaced the DPFE with a new one from Rock Auto but the code still reappeared. I applied vacuum to the EGR valve. The poppet valve moved in and out and the idle got rougher, but did not stall. If the EGR is ok then I read on the posts that the tube should be removed and the passages cleaned. Does anyone know the size of the lower large nut? It looks like a tough place to get at and wonder if it will even come loose and what tool to use. Should I soak the various fasteners first? I figured I could remove the upper nut after the lower one is removed and I also remove the EGR with the tube still attached.
Please let me know the right way to approach this.