Where are the oxygen sensors on a 1999 GMC Savana?

On a 1999 GMC Savana, the oxygen sensors are typically located in two main areas: one before the catalytic converter (upstream sensor) and one after the catalytic converter (downstream sensor). The upstream sensor is generally positioned in the exhaust manifold or just after it, while the downstream sensor is located on the exhaust pipe after the catalytic converter. To access them, you may need to lift the vehicle for better clearance. Always consult the vehicle's service manual for precise locations and details.