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I get a PO400 code (EGR malfunction) after a 40 mile freeway drive and come to a stop at the exit. Dealer can find NO problems anywhere except to say that to solve the problem I need to put the stock exhaust back on because the loss of back pressure is what is tripping the EGR code.
Same issue here. 1996 LT1 Vert. I have factory CATS, resonator removed, straight pipe going into Magnaflow Axlebacks. I can clear the code, after about 20 miles of driving code returns.
Same issue here. 1996 LT1 Vert. I have factory CATS, resonator removed, straight pipe going into Magnaflow Axlebacks. I can clear the code, after about 20 miles of driving code returns.