2000 Ford Taurus (PO430 Code)

To check that problem requires sort of an extensive series of pinpoints to figure out if the bottom line is that the cat is chemically dead. Along the way, there could be issues causing the code that don't indicate the cat is bad, exhaust restrictions, leaks in the exhaust system, is the fuel pressure good? Any work done on the rear 02 sensors before this happened? Crossed wiring could cause this, as could a damaged pcm unit. Could be a job for the dealer, you need someone qualified to do these diagnostics, dealer or otherwise.

Ford has had issues with faulty or malfunctioning tank sending units for years, resistance issues usually where the tank may read full at first then drop up and down finally working correct when tank is almost empty, weird stuff like that. Do you have a low fuel light? Does that still sort of work correctly? I wouldn't spend the money, not cheap, to fix it unless you could drop the tank yourself, I'm not 100% on whether the sending unit in your year is a separate piece from the fuel pump may or may not be. Excessive fuel pressure could be a contributing factor withy this code you're receiving, that is one of the tests that would be done along the way.