Thanks. I will measure it on the weekend and let you know

 

Hi, I have a 2001 as well and had the P0420 code awhile back (if you search the forum you can probably find it pretty easy).

For mine, I checked for vacuum leaks going in, none found. Used the SeaFoam to clean out the carbon and make "smoke" to check exhaust. Do you smell a slight exhaust scent at all? I had a faint smell and the flex pipe was leaking, fairly easy fix. The catalytic converter was also bad (241K on the car). Flex pipe and Magnaflow converter were all direct fit, all bolted on, under $200 after recycling the new cat.

My CEL just came back on but this time a vacuum leak at the intake (that long tube from the air filter box to the manifold), cracked a long time ago and have been duct taping ever since, although used electrical tape in a pinch a few months back, bad idea, didn't hold up to well.

Just my two cents.

 

I just had a very similar thing with car I bought, but didn't know the history. I would make sure to go with a Denso O2 sensor. I bought a Bosch and it made my car run horrible. Changed it out and ran like new. I also had a cat code p0420 and after I changed O2 sensor it went off, but my cat was done for. It was rattling like crazy. Good luck...

 

I don't see any visible cracks in the intake tube or any sign of leakage. I will check it once more just to be sure.

I have ordered Denso O2 sensor from Amazon. It's much cheaper on amazon than buying at local part store. It should be here in few days. Will replace that first and then go from there.

Thanks for sharing your experience.