Error code P0420 help

[Tyler2]

I have a 2001 4 cylinder camry with 120,000 km on it. Today the check engine light came on and my code reader is telling me its P0420. I realize this is indicating an issue with the catylitic system and could be the upstream or downstream o2 sensor, or the converter itself. Just wondering if anyone had any suggestions as to which to look into first? i.e what is the most common reason for this code.

Thanks in advance

Tyler

[deejayphilo]

I got this from somebody else...
Your situation is exactly like mine, at 145k miles. I changed out the O2 sensors and the check engine light went out and I just passed inspection. I googled what the O2 sensors looked like, then found one in the front of the engine and the other just under the front end. It cost me $110 for one, and $125 for the other due to the longer cord to the connector-and I had to buy an 02 socket for $10. When the sensors are fouled, you get a bad reading of Catalytic Converter problems that don't exist-these sensors read Cat problems, but if they don't work they give you bad readings and the check engine light. We unhooked my battery to let the computer restart and it solved a low idle problem I had as well. I hope this helps!

[deejayphilo]

That is a no rush problem to fix unless you smogging...

[Tyler2]

Thats what I figured I should check first, I will take a look at them tomorrow, I have been reading up on it and I guess you can check them by reading the voltage off them. I know this isn't I huge deal, I just don't like having unresolved engine lights, kinda anal about it.