This helped, I didn't know about the LED. I got EGR valve (code 34) with nothing connected, EGR valve and O2 sensor (code 32) with the white memory plugs connected, and 5 with the green test mode connectors. The only place I find 5 is here:
which implies that it's good. It says here:
that a dealership technician can perform dynamic tests. What does that mean?
And can either a bad EGR valve or O2 sensor affect performance? Or are they only emissions related?
O2 will definitely affect performance - depending on how bad it is, the car can become almost undrivable.