Hey guys, I am having a problem with the O2 sensors on my 95 Ranger with a OHV 4.0 with a manual transmission. The CEL has been coming on and i keep getting the codes P1443, P0135, and P0155. The codes are O2 sensor malfunction bank 1, 2 and manufacturer emission control malfunction. I have replaced both O2 sensors cleared the codes and the CEL keeps coming on. I have checked both harnesses and plugs for damage and everything looks fine. I am about to pull my hair out! Any help or suggestions would be much appreciated.

 

Should I replace the O2 sensor after the cat or would that be a waste of money?