Where are the oxygen sensors on a 1998 Toyota Avalon?

On a 1998 Toyota Avalon, there are typically two oxygen sensors: one located before the catalytic converter (upstream sensor) and another after the catalytic converter (downstream sensor). The upstream sensor is positioned on the exhaust manifold, while the downstream sensor is found on the exhaust pipe, just before the catalytic converter. Accessing these sensors may require lifting the vehicle for better visibility and reach. Always consult a repair manual for precise locations and procedures.