Yes it may set a code but is not nessasary. Once the computer detects it doesn't work, it no longer compensates. I kept the system on in my old car but blocked it at the intake to cylinder head to keep hot gasses from entering the intake and heating it up. Then I disconnected the coolant lines that go to the EGR plate, this all made a difference in how hot the intake got. Power difference? Don't know but it couldn't have hurt keeping the intake cooler. Every little bit helps.