Q&A

Catalytic converters are federally mandated to be warranteed for 8 years or 80 000 miles. If you are still within that, then they are a warranty item. Exhaust leaks, and faulty oxygen sensors can also cause this. Faulty catalytic converters on a high mileage vehicle, however, are very possible. There does not need to be an odor, since sulfur has been essentially eliminated from gasoline. VSA and TRAC is the vehicle stability control and the traction control. A problem with one, will disable both, and illuminate both lamps. The traction control may be deactivated by a switch on the lower left of your dashboard. Switching off the traction control will also illuminate both lamps. Make sure the switch is in the on position. If it is, then you will need your vehicle scanned to identify the problem in that system as well.

Great answer by "devilscap4", I would plug in a scan tool and look at O2 sensor patterns especially the rear sensors to see if they are oscillating a lot or relatively flat as they should be if the catalytic converters are good.

You already have 2 excellent answers from 2 great tech.
Here is what I'd like to add:
Was your vehicle manufactured between February, 2003 and April, 2003 and your VIN range is between 40001284 and 40006137 or between 40001700 and 40012110 ??
If yes, there is a recall from Lexus and they will replace the converters for free, even if you are out of the 8 years/80K warranty.
Recall / Campaign #: SSC3LE
Let us know what happened.

Zee

Mine did the same - intermitently. My private shop said the ECM reported a LEAN condition on the left bank and suggested I run some fuel injector cleaner thru it. I did so last week and it has not YET come back on.

Good luck!

Gino