1989 gmc sierra 1500?

[Trevor T]

Where do I find the O2 sensor on the vehicle and how do I replace it?

 

[bigboro718]

the oxygen sensor is on the exhaust manifold . if you go to a part store like autozone they will have the tools u need

 

[Sam Chicklets]

It's on the drivers side exhaust manifold by the flange where the exhaust pipe bolts on.