How do I fix code p0430?

Question

I've replaced both cats all 4 O2 sensors still coding out. What should I replace next

Answer 1

P0430 Catalyst system below threshold (Bank 2)

Check and inspect the condition of the overall condition of the engine, In order for the catalytic to work effectively the engine has to be able to have fuel control, This begins with its abilty to have a proper working igntion system

 The sparkplugs should be the first to check, a ignition misfire will rapidly deteriate the catalytic convertor from working properly, Here a set of worn out sparkplugs set a P0420 and a P0430 , the reason is when the sparkplug gaps widen incomplete combustion is the result.

 Installation of the catalytic convertor is also important, There can not be any exhaust leak prior to the catalytic convertor. Here is a Chevy 1500 with a 5.3, newly installed catalytic convertor that coded a P0420. (catalytic below threshold Bank 1) , A code was set, even with a new 02 sensor, the reason exhaust leaks prior to the catlayic convertor, this affected the catalytic from going rich to lean and instead the rear 02 sensor just read the system as lean. In this case the catalytic never has a chance of reaching its operating temperature.

 The oxygen sensor, A proper working front 02 sensor which is the engine management sensor has to be secured, what looks properly secured was not. Even with the engine running and gripping the 02 sensor it is turning , being not properly torque down set a P0420 (catalytic below threshold Bank 1) code condition , The reason the 02 sensor could not properly read , What a 02 sensor is is no more than a temperature coefficient sensor, it read temperature of the exhaust system this determines if the engine is rich or lean Being loose always gave it a lean reading condition without setting a 02 sensor code,