On a 2001 Chevy Silverado 1500, the Bank 2 Sensor 1 O2 sensor is located on the exhaust manifold or exhaust pipe
after the catalytic converter on the passenger side (right side in the US). "Bank 2" always refers to the passenger side bank of cylinders, and "Sensor 1" is the sensor closest to the engine (before the catalytic converter). Since this is Sensor 1, it's before the catalytic converter. This is important because it means it is measuring pre-cat exhaust gases and provides feedback for fuel mixture adjustments.
It's important to visually confirm its location as the exact placement may vary slightly depending on the engine configuration (4.3L, 4.8L, 5.3L, or 6.0L). Consult a repair manual specific to your truck's engine for the most accurate diagram. A diagram specific to your VIN is often the best.
