* Upstream O2 Sensor: Located in the exhaust manifold or very close to it, before the catalytic converter. This sensor is the most important for controlling the air/fuel mixture.
* Downstream O2 Sensor: Located after the catalytic converter. This sensor monitors the efficiency of the catalytic converter.
To find them precisely: You'll need to consult a repair manual specific to your 2000 Grand AM's engine (e.g., 3.1L V6, 2.4L I4). These manuals will have diagrams showing the exact sensor locations. You can usually find these manuals online (for purchase or sometimes free PDFs).
Without knowing the engine size, I can't give more precise directions. However, both sensors will be in the exhaust system's piping, likely threaded into the exhaust pipe itself. They are usually wired into the vehicle's harness. Be careful when handling them, as they are fragile.
