The car does have a "limp mode" but the codes you are throwing aren't going to cause you to end up there. I'm surprised the resistor didn't help with the CEL; did you put it in the correct spot? It should be spliced inline on the rear O2. If it really isn't working you could always try the one that Mastro sells, it's been working great for me and I haven't throw a related code since installing it. Other then that it isn't anything to worry about, the code is just letting you know that you are polluting the environment.