need help with o2 sensor code

[bird of fire]

This past week I have changed my valve cover gasket , did a egr block off. To get have to take the right header off . I have had the cpu tuned and i got this code went i started it up and got this code P0153 Heated Oxygen Sensor (HO2S) slow response Bank 2 Sensor 1 . I do not know why?

[BLLDOGG]

Re: need help

sensor is probably taking a dump.

[bird of fire]

Re: need help with o2 sensor code

I ran it for 40 min an no dtc's