my friend's 2000 civic is throwing a code 67, which is apparently catalyst low efficiency. i don't think her cat should be bad already since it's still a pretty new car. any suggestions? thanks.

 

My understanding is that a catalyst can get bad very quickly if abused. That is if the engine was out of tune and fouled it up. Or it could be a bad catalyst from the start. It is expensive to put another in and then find out it is a sensor issue. You could try to pick one up at the junk yard to test, but I doubt they will give you one as I think it is illegal in most states to sell them used.