Was a P0420 code, after a week the light went out?

98 EX Accord coupe, V6, auto, 110,000 miles
I've been driving for a week and a half with a P0420 code. (or was it P0240? anyway it was a problem with the cat). I have an appointment to bring it in
tonight. I didn't drive the car all weekend and when I started it up this morning the engine light has gone out...
What would this indicate? Would any codes be stored or does the light have to be on for my mechanic to diagnose the problem? I have some other issues that need attention so I'm going to bring the car in anyway and talk to my mechanic I was just wondering what was going on with the light.
It would be nice if I didn't have to replace the cat...$$$$
TIA
Steve
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I had the problem on a '96 and it wasn't the cat, rather the downstream O2 Sensor. Dealer wanted $235 for a new one (part only). I got a DENSO for around $70 and installed myself. AutoZone loaned me the special socket to remove and install. Get some Break-Free and let it soak for a few hours on the threads of the sensor.
I hope yours is as easy.
G-Man

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After 100K miles,the other O2 sensor may be getting sluggish,too. (and still not set a trouble code) Lifetimes I've seen published are 60K to 100K miles.
--
Jim Yanik
jyanik
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