Topic: 97 runner check light on and need some help

[Misfit4Runner]

on my way home from the beach my check light came on so I pulled into an autozone and heres what they got.
Troubleshooting code : P0420

The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank1 identifies the location of cylinder#1, while bank2 identifies the cylinders on the opposite bank)


Definition
    Catalyst efficiency low-bank 1
Explanation
    The oxygen sensor monitor the catalytic converters ability to store oxygen
Problem Causes
1-Catalytic Converter defective (failure possibility due to #2, 3, or 4)
2-Engine misfire or running condition
3-Large vacuum leak
4-Engine oil leakage into exhaust-vaule guide seals, piston rings


Ok so thats what the print out said. Now its a 3.4 and I'm getting around 300 miles to the tank It didn't seem to have any loss of power when the light came on and sounds to be running smooth as it ever has. As far as a vacuum leak I got some sensor safe carb cleaner and sprayed it around the intake to see if it would rev (that is the correct way to do it right)  and it didn't. The dealer replaced the converter about 2,000 miles ago. and as far as leaking oil.. I don't seem to be blowing smoke  that I can tell of. But I am gonna have my wife rev it up so I can check then too..
Any and all help is always appreciated! 
thanks!

[BruceTS]

P0420 means your catalytic converter isn't working at it's peak efficiency, in laymans terms you have 2 O2 sensors, one in front of the converter and one at the back. If the reading on the back sensor isn't lower than the front is showing it will throw a code. Don't let the Bank 1 or 2 confuse you, all the cylinders exhaust out the same pipe.

Now how to fix the problem, first reset the CEL, by disconnecting the battery cable or pulling the EFI fuse.  If the light comes back on again then you need to test the O2 sensors. You could have a failing sensor, but not throw a code.

Typical readings.....O2 Sensor1 Val ---------  .65 Volts O2 Sensor2 Val ---------  .495 Volts

Now if you are still getting a code with the O2 sensors operating properly, get the emission output checked, if they are within tolerances, the converters are working well enough, but below the factory standards hence the CEL. To eliminate the problem without replacing the cats is simple by adding a box to fool the system in believing everything is OK. To do this you'll add a Rear Oxygen Sensor Simulator from URD. This will eliminate the code and won't be noticable during a smog test.