This useful automotive tool will allow you to monitor the battery voltage, the airflow meter, or oxygen sensor in your car. It's powered by 12V and features a 10 LED indicator that illuminates in response to the measured voltage so you can see if your O₂ sensor is causing your car to run too rich or too lean. Preset 9-12 volt, 0-5 volt or 0-1 volt ranges, complete with fast response time, high input impedance and auto dimming for night time driving.