I have a KIa sportage 02, I have always the codes P0134, P0135, P0136 , and P0141, what could be?

Question

I installed O2 sensors, but same problem. , the catalytic converter is missing.

Answer 1

if you dont have a catalytic converter that is the reason the lights are on. You need a catalytic converter to pass smog. you might be able to install oxygen sensor non fouler but you wont pass smog