Code 0430 on '96 t-bird

I used to get the code about every 15k miles, but now I'm getting it every couple of weeks. I don't have the readout right in front of me, but I think it's a code 0430: catalyst efficiency out of spec in bank 2.
Is this a known weak sensor or do I have a cat. going out?
I previously thought it was happening whenever I used Amoco gas, but now it's happening with others. Could fuel be an issue here, or is it just coincidence?
I'm due for an oil change in about 2 weeks, and I will have the dealer look at it then. I'd just like to be prepared if they're going to tell me my ride is hosed.
Car: 96 tbird 4.6
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Some research on this fault code indicates that it is the most common one that registers on cars with over 75K miles. It apparently will be triggered more often as catalyst performance goes down. It's not supposed to trigger unless efficiency is degraded to the point that emissions would in fact measure 1.5 times allowable EPA limits. Most cars with this fault code when put through an EPA emissions test, will actually pass. So, unless you want to fork out the bucks for a new cat, keep resetting the light. The annoying thing about these false alarms is that they will mask any other more significant codes unless they have been reset.

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There are a number of things that will cause the catalyst efficiency monitor codes besides a bad sensor or converter. Leak in the exhaust between exhaust manifold and converter. Mild engine miss. Fuel pressure too high. Oil in the combustion. Incorrectly operating thermostat. Incorrect spark timing. If there is an air pump, it not plumed correctly, or direction valves not working correctly.

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I'll have to watch how often I get a 0420 (Low efficiency on bank 1) code on my 97 Taurus 3.0 now - was getting it every couple of weeks. Just changed the plugs and wires for the first time at 100K - I know it was way overdue, and the plugs showed it. So, a mild miss (the car was actually running OK on the lousy plugs) may have been my cause.

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Not sure what you are asking.

Not all misses will be picked up by the processor. It depends on the severity of the miss. A dead miss will be picked up, a very mild will not be. It's a common misnomer that the engine computer is the know all do all device very close to a god. The point I was making is that just because you received a code for the catalyst efficiency monitor does not mean that you automatically replace the converter and or sensor as a lot of "mechanics" will want to do or people in this NG will tell you to do. Before any part is replaced there should be a complete diagnosis made to rule out one of the above possibilities I mentioned. The important thing to remember is that the sensor is only reading what come out the converter. Anything that will change the gas content before it enters the converter can give an out of range reading. The code is only a clue.

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