Seeking cure for repeated P0420's and P0430's on my 2002 LS430. My independent garage has replaced the left catalytic converter three times and the right converter twice in the last nine months. After paying for the first pair of converters, all costs have been covered by warranty, but the codes are still being generated. This weekend they plugged a recorder into the computer port to gather data for analysis.
* Not sure if my shop will be able to cure my car. Thinking I should just let the dealer take over this problem. My independent shop has tried its best, but I think it's beyond their capability. Any thoughts on curing this problem?