Where is the bank 1 oxygen sensor on a 1999 Pontiac Grand Am SE 4 cylinder?

On a 1999 Pontiac Grand Am SE with a 4-cylinder engine, Bank 1 is the side of the engine that contains cylinder #1. The oxygen sensor location *for Bank 1* will be on the exhaust manifold or the exhaust pipe very close to the manifold, before the catalytic converter. You'll likely find it near the front of the engine.

To be absolutely certain:

* Consult a repair manual: A Haynes or Chilton repair manual specific to your year and model will show a diagram with the exact location of all sensors. This is the most reliable method.

* Use a parts diagram: Many auto parts websites (like AutoZone, Advance Auto Parts, etc.) allow you to select your vehicle and view diagrams showing sensor locations.

Without a visual reference from one of these sources, pinpointing the exact location is difficult as there can be slight variations. However, the general area described above is where you should focus your search.