How many oxygen censors are there on a Volvo 1996 850 GLT?

The 1996 Volvo 850 GLT typically has two oxygen sensors: one located before the catalytic converter (upstream) and another after it (downstream). The upstream sensor monitors the air-fuel mixture, while the downstream sensor checks the efficiency of the catalytic converter. It's important to verify the specific configuration, as variations might occur in different models or engines.