I have a 2000 v-70 with 100.000 miles showing a code PO-422 ( main catalist efficiency below threshold,bank#1),the counter guy at the local parts store said that the catalytic converter might be going out and triggering the code,he cleared the code and suggested adding fuel system cleaner to the tank,I added Lucas injector cleaner and drove 300 miles over the next 7 days w/o a warning signal.yesterday the check engine light has come on a couple of times while driving but never stayed on.I will have it checked to see if the same code PO-422 is back,my question is this.Is the parts guy with the scanner on the rite track?is it poss to clean out a cat?and what else would cause that code? the car starts and runs fine as it always has,even when the light stayed on,idles smooth,no smoke, any feedback would be appreciated.thanks