Hi all,

I’ve got a 2003 Nissan Maxima GLE, and the dreaded PO420 code has come up right when I need to get it smogged. It came up a while ago but my friend bought some cheap O2 sensors and replaced the front and back. One thing is that the colour of the cable is green while the receiver is blue and they don’t quite fit like a glove. Is it possible that he got the wrong O2 sensor?

How can I tell if the problem is the O2 sensor and not the Cat?

Thank you very much in advance.

 

Unless you a muffler expert, most likely you cannot with the Caty.

a muffler shop can tell if the cones in the Caty is bad .....

most times that’s the underlying cause that will wear out the O2, then cause a code.....

pick your poison.