Code

[Tony's backyard]

Hi,I'm new to this four pardon me if I make a mistake. I just want to ask question regarding code P0420 it say bank 1 which sensor this refer to? It is before cat or after. Thank you very much.

[CTScott]

0420 is Catalyst efficiency below threshold, which can be an issue with either sensor, or can be due to an exhaust leak or cracked manifold.

[Tony's backyard]

I check a possible leak,I don't see or hear a leak. If you say could be a sensor which sensor is that?

[CTScott]

I check a possible I don't see or hear a leak. If you say could be a sensor which sensor is that?

If you don't have an exhaust leak, then it is more likely a bad cat, than one of the two sensors.