Check your diagnostic trouble codes if you think your Pontiac oxygen sensor is ailing or failed. Perhaps you noticed that your engine is emitting too much pollution and the gas mileage is dropping. Or, when you hit the gas pedal to accelerate, your engine hesitates or bucks. Those symptoms are indications that something is wrong with the combustion or fuel system in your LeMans or Catalina. These problems, for example, appear when the fuel injectors are clogged. If you run a diagnostic code check and see #12, then it is possible that something is interfering with the circuit between the sensor and the Electronic Control Unit. Loose wiring or poor grounding can do that in some oxygen sensors that have up to four wires. Those are for sensors that rely on a small 12V heater to preheat the sensor to high enough levels that activate the voltage carried between the sensor and the ECU. However, be aware that if the oxygen sensor is simply slow to respond, the diagnostic code might not register any problem. In cases like that, you would have to try a digital oscilloscope, which will measure whether the oxygen sensor is swinging back and forth in its voltage levels at the proper rate. A little detective work might then tell you whether it is time to replace your Pontiac oxygen sensor. If you make that determination, order a new oxygen sensor here, and then install it yourself.