04 kia codes p0431 & p0421 what else can be done other then intake?

Question

2004 kia sedona ex p0431 & p0421 are coming up on my dtc code reader. After car warms up, the engine starts to vibrate a little. my question is what would be the first i would need to take a look at???

Answer 1

P0421 Main catalytic efficiency deterioration (bank1) 

P0431 Main catlayst effiecieny deterioration (bank2)

This codes does not necessarily mean you have a catalytic problem but a condition that is contributing to it.  A visual inspection needs to be done first, The MAF (mass airflow) Check the air duct to the throttle body for proper connection and there is no air leaks that will cause false air.Do a MAF  cleaning (mass air flow sensor may be a seal type and cleaning may not be possible).The spark plug ,check their condition if they are worn or in need of replacement they should be replaced, Timing belt , Kia uses a hydraulic tensioner, timing belt alignment marks is they are off slightly can contribute to a catlytic code condition