When your vehicle shows a bad oxygen sensor, you should take certain measures to address this issue. The oxygen sensor plays a crucial role in the vehicle's emission system by monitoring the oxygen content in the exhaust gases and assisting the engine control system in adjusting the fuel mixture ratio. A faulty or malfunctioning oxygen sensor can lead to decreased vehicle performance, reduced fuel efficiency, and even adverse environmental effects.

Here are the steps you should take when you spot a bad oxygen sensor:

1. Observe the warning indicator: When the oxygen sensor is faulty, the vehicle's check engine light may illuminate. If your vehicle's diagnostic system displays a warning signal for an oxygen sensor malfunction, pay attention to this indicator light.
2. Locate the faulty oxygen sensor: Determine the location of the malfunctioning oxygen sensor based on your vehicle's make and model. A vehicle typically has multiple oxygen sensors, including those positioned before and after the exhaust system.
3. Check sensor connections and wiring: Inspect the electrical connections and wiring of the oxygen sensor to ensure they are not loose, damaged, or corroded. Sometimes, the issue might be due to loose connections or corrosion.
4. Replace the oxygen sensor: If you confirm that the oxygen sensor is damaged and cannot be repaired, consider replacing it. Purchase a new oxygen sensor that is suitable for your vehicle's make and model, and follow the manufacturer's instructions for installation.
5. Clear fault codes: After replacing the oxygen sensor, use an OBD-II scanning tool to clear the fault codes. This will reset the vehicle's check engine light and ensure proper functioning of the new sensor.
6. Regular maintenance and inspections: To prevent issues with the oxygen sensor, regular vehicle maintenance and inspections are crucial. Follow the manufacturer's recommendations for timely replacement of oxygen sensors, and ensure the exhaust system and engine remain clean.

Please note that the above steps are provided for reference purposes only. If you are unfamiliar with car repairs or unsure about how to proceed, it is advisable to consult a professional automotive technician or visit a specialized auto repair shop for assistance.