Help!! Catalytic Converter update

I went to get the Catalytic Converter last week and it had not come in as promised. By the way...The light went off again 2 days before.
I asked the garage what if I changed the Converter and then Sensor and still had the light, how would we handle me paying $350 for repairs that did not work. He said I could do a $ 50.00 test that would give a good idea....Hmmmmmm...I explained my money situation (lack of) and he said to just drive the car since the light went back off. As I said earlier the car is driving fine. My question is....Could I get the Code PO420 and it be something else or maybe just a clog in the converter that could unclog? I hate that the repair is not 100% a sure way to fix the problem.It has now been around a week and no warning light. Any thoughts?

The cataylic converter reduces hydrocarbons, carbon monoxide and nitric oxides to a lower number. So the $50. test is probably a smog check which will measure exhaust gases to see if they are within specs. If the test shows the gases are OK, the cat is probably OK. You don't say what year the car is but if it is old, the cat will probably need replacing somewhere down the line, so the investment isn't completly lost.

do the test, see if its the cat converter, if its not, then your sensor is just not working properly, so if its just the sensor then you dont have to change it, it wont harm anything

Sorry I left out that it is a 1998 Accord EX with 109,000 miles on it. I recently changed the plugs but could not get to the rotor. If it needs changing could that affect performance and the light?

A catalylic converter should last a lot longer then 110K miles. I don't have the manual for your car so I can not help you on codes. Sometimes ECL lights come on and then go off. So you should reset your computer and see if ithe comes back. If it doesn't just drive it until you see another problem. By the way, you did change your timing belt on schedule correct?

The light started coming on right after Hurricane Dennis came thru and messed up our normal gas supplies. I went to some small out of the way stations to find gas.Just wondering if bad gas could of set it off?
The light came on and I went to Autozone and they checked it and got P0420 code. They would not reset it because someone got accused of messing up a car onetime, so they don't reset around here anymore. Honda told me to take neg. battery cable off to reset. It did make light go off. Then it came back on a week or so later. Went to another Autozone to double check and got same code again. Light went off again. Then on for a week and now it has been off over a week. Yes, I just changed my timing belt around 98,000 miles. I don't know if I am imagining that the car is running noisier or not but it runs fine and getting 30mpg w/ac on. Muffler guy put it on a rack and could not see any problems but put some device on the converter and said it was hot in the back???

A catalylic converter should last a lot longer then 110K miles. I don't have the manual for your car so I can not help you on codes. Sometimes ECL lights come on and then go off. So you should reset your computer and see if ithe comes back. If it doesn't just drive it until you see another problem. By the way, you did change your timing belt on schedule correct?

Hot in back is a good sign. That means the converter is working. Don't know how well but it working. Bad gas could cause it especially if it is leaded. (Don't know if anybody still has that stuff though) The code could be a bad sensor, bad wiring or a converter that is on the lower limit of its operating curve. So I guess the test might be the cheapest start to resolving your problem.

I did have to get leaded one time. But only once. I guess I will let it ride unless the light comes back on or it starts bucking like a wild horse :-)

Leaded gas can poison the cat converter by coating the platium screen. Then it does not burn the hydrocarbons. So it could reduce the efficiency which could cause the light. The test will show how good the converter is performing.

another major enemy of the cat is misfires. You said you changed the plugs. Im just wondering if the plugs (if they were bosch) could be creating a subtle misfire and then the cat went bad.

Regardless its still a bad cat whichever way you slice it.