GX 470 Catalytic Converter issue after new alternator?

[TVW]

Just had a new OEM alternator installed on my 2005 GX 470 while traveling. A legitimate repair...was only putting out about 6 volts. 130,000 miles on car.

Drove 250 miles to next town. The next morning all the lights on dash lit up. Went to Lexus dealer...scanned code P04030. New Cat system recommended: $2787.00. Anyone see the potential of a coincidence? Perhaps something occurred during alternator installation at independent repair...connection, etc? Just a shot in the dark, but would appreciate any feedback. I did disconnect the battery ground for 20 minutes and the lights went off and stayed off but my bluetooth scanner gives me the same code. Runs perfectly and the rest of the car is 9+ points. I'm in $$ California so I may have to give it to one of my kids who prudently bailed to Oregon and Idaho. Ideas? Thanks. 

[lenore]

I cant find that code, is it p0403? 

[lenore]

Or P0430?  Just a bit of info, you might just have a cracked vacuum hose on the intake somewhere.  Cats generally don't go bad, they get contaminated with oil, etc.  They can be cleaned with commercial cleaners or even just plain water.