P0430 code

Plugged in my scanner and threw p0430 code bank 2 efficiency below threshold. Changed my o2 sensors downstream & upstream and still throws a code. Truck has 187k miles. Do I need a new cat ? I bought an exhaust manifold but haven’t installed it yet

 

Could need a new cat or a leak. Check leaks first as that's the easiest cheapest.

 

Did you replace them with OEM denso sensors? These trucks don’t like certain non oem stuff.

 

Do you have an exhaust manifold leak? If you do, it's possible that the exhaust is scavenging air and not sending a correct value to the O2 sensor. You may have to fix the exhaust issue first, before moving further.

 

@revtune yeah I used Denso o2 sensors. @N84434 I’m suspecting an exhaust manifold leak I noticed the manifold was very black near the upstream o2 sensor and only in that area.