Toyota Repair: OBDII Code Clearing, obdii scanner, monitor test

Question
My 1996 Camry has a P420 code.  Just bought it with 293,000 miles. Trying to get tags in WA.  I have a cheap OBDII scanner that can delete codes.   How long will this code stay deleted?

Answer
The code will stay deleted until the next time the computer runs a monitor test on the converter, which is continous and will run after each time the engine is started, if your'e thinking of getting it passed before the light turns on again then clear the light just before the test, it may work.