I need Help with the Exhaust gas sensor warning Thing

[needhelpbad87]

I have a 1986 nissan 200 sx and the sensor light is on in it i figured it was the oxygen sensor because in the manual it say its for an exhaust gas sensor so i figured it was the oxyegen sensor but ireplaced that amd the lights still on an the same problems are happening as they were when the old sensor was in so im just wonderin if anybody has any ideawhat i need to do if so plz let me know these problems are very annoying thanks alot

[sideways]

look for a button under the dash on the passenger side according to the fsm after you replace the o2 sensor twice you should use this switch