Cat converter or o2 sensor(s)??

[BikeHauler]

The check engine light on a 96 Camry with 100,000 miles + came on. The code says "P420 Converter below threshold."

Before I buy a catalytic converter, I thought I'd poll the experts here and see if I should check the 02 sensors and if so, how do you check them with a digital multimeter?

It looks like the converter is fairly easy to replace; izzat true? Also, there's a rattling noise coming from the front of the engine on startup...could that be related to this problem?

Any advice on pricing and replacing the catalytic converter? Dealer cat is out; way too expensive. A cat from a junkyard is cheap but too iffy--what if it's bad, too?

Your advice appreciated.

[TRDragoon]

well, you got few option.
1) goto the dealer, or anybody with OBDII to check whats the cause. you can get direct signal if its the O2sensor. it'll read low voltage signal from O2sensor.

2) the noise you say its rattling, go undernieth the car and tap the cat with a rubber mallet or anything like it, and if you here rattling noise, its your cat.

3) you can take out the cat, and inspect yourself. once you look inside and if you see a complete "comb" sealed, theres no prob, but if you see a small thru the cat, your catis gone.

4) i dunno if you camry is a 2 way cat (lowers CO and Nox) but if so, its lot easier with OBDII....cuz there should be one O2sensor on the 2 way cat, and i think what the code is saying is theres lack of oxygen in your cat...

well, i dunno this helps but g luck!