Code PO 420

I have a 2003 silverado 4.8L. 2wd with 130,000. I keep getting code 420. Any help? Does not seem to have an exaust leak.
Thanks

Its letting you know that your catalytic converter efficiency is low. It has nothing to do with exhaust leaking

I have a 2003 silverado 4.8L. 2wd with 130,000. I keep getting code 420. Any help? Does not seem to have an exaust leak.
Thanks


swap down stream O2 sensors if problem dtc changes its the O2 sensor,,,if it don't change its the cat converter....

if these o2 sensors are 130,ooomi on them you need to replace them...100,ooomi is the recommended mileage to replace...