52mm Digital Air Fuel Ratio Gauge With Narrowband O2 Oxygen Sensor Car Gauge AFR Fit for 12V Car Voltmeter 2 in 1 Meter VoltageFeature:- High Precision - Racing look enhance the characteristic to your car/vehicle - Fitment : Universal 52mm diameter Voltmeter fit for Motorcycle Car /Truck/ Gasoline Engine (The compatibility just for reference .Please make sure the item fit for your car before purchase.)Fitment:Fit most of 12Volt gasoline vehicle, Fit 2 or 52mm Diameter Gauge Pods holderApplication:Color:Black Voltage:DC 12V Diameter:52mm/2 Material:Plastic Quantity: 1 SetPackage Included: as the picture shows1x Air Fuel Ratio Gauge OR 1x SensorNote: The gauge cup needs to be purchased separately, the gauge does not contain the gauge cup O2 sensor instructions- The white line is at heater ab - Black line signal line C, gray line signal ground D - The green wire of the instrument is connected with the black wire of the sensor. - The gray line is connected to the negative pole of the battery. - One white wire connect with the car shell or battery negative pole. Another white wire connect to the ACC line of ignition switch - The white line is the heater and does not distinguish between positive and negative electrodes - About the air fuel gauge, please see the installation instructions