Where would you find the O2 sensor in your 2001 Chevrolet impala?

On a 2001 Chevrolet Impala, the oxygen (O2) sensors are typically located in the exhaust system, before and after the catalytic converter. There will be at least two, possibly more depending on the engine configuration.

To be more precise:

* Upstream O2 sensor(s): Located in the exhaust manifold or very close to it, before the catalytic converter. This sensor is crucial for controlling the air/fuel mixture.

* Downstream O2 sensor(s): Located after the catalytic converter. This sensor monitors the efficiency of the catalytic converter.

You'll likely need to look underneath the vehicle to locate them. They are usually threaded into the exhaust system and have a wiring harness connected to them. A repair manual specific to your 2001 Chevrolet Impala's engine (3.4L, 3.8L, or 5.7L V8) will show the precise location with diagrams. Consulting a repair manual is highly recommended before attempting to locate or replace them.