Where are the o2 sensors located on a 2002 GMC Sonoma 4.3L 4wd?

On a 2002 GMC Sonoma with a 4.3L engine, the O2 sensors are located in two main positions. The first sensor, known as the upstream or pre-catalytic converter sensor, is situated in the exhaust manifold or just downstream of it. The second sensor, called the downstream or post-catalytic converter sensor, is located in the exhaust pipe after the catalytic converter. Both sensors are critical for monitoring exhaust emissions and optimizing engine performance.