Your Oldsmobile oxygen sensor is part of a network of sensors that the car's computer relies to help regulate the combustion cycle. Unlike the other sensors, the Oldsmobile oxygen sensor is located near the exhaust manifold, where it measures the oxygen levels of the residue of the combustion cycle. The goal: that perfect oxygen-to-fuel ratio of 14.7:1. Other sensors inform the Electronic Control Unit about the flow, volume and turbulence of the fuel and oxygen coming into the combustion chambers. Using all that data, the ECU regulates the flow of the fuel that is emitted from the fuel injectors. When the oxygen sensor is not running, the ECU relies on the other sensors' data. Normally, that means that the engine will receive a higher mix of fuel, and slightly less oxygen (ie: a 'rich' fuel). Over time, that rich mixture will damage the catalytic converter in your Oldsmobile. Too much fuel in the combustion cycle will mean that excess fuel will be emitted from the exhaust; that will raise your gas mileage and the hydrocarbon levels in your emissions. If the Oldsmobile oxygen sensor begins to be sluggish, the ECU might be confused by the data and will run both too lean and too rich. The first step to pinpointing whether the oxygen sensor is failing - or whether the other sensors in the combustion/fuel systems are dying - is to check the diagnostic codes. Be aware, however, that often the oxygen sensor will display intermittent sluggishness, so the lack of a diagnostic code may not mean anything.