AEM has a comprehensive line of highly accurate, reliable wideband air/fuel controllers that can help ensure your vehicle is optimally tuned. WHAT IS FREE-AIR CALIBRATION? Some of our competitors require that you frequently perform a free-air calibration procedure to calibrate their O2 sensors. This process involves removing the sensor from the bung while still connected to the controller device, then waving the sensor in the air so it can read atmospheric O2 levels. We use 4.9 LSU sensors in our wideband controllers. Our sensors are individually laboratory-calibrated and never require free air calibration! CAN I CHANGE THE AEM UEGO SENSOR'S CONNECTOR? No. There is a laser-etched, calibrated resistor in the sensor's connector body. This resistor is specifically created for the exact sensor that it is attached to. Modifying this will invalidate the sensor's output. Center LED Readout Displays Gasoline Values from 10 to 18 :1 AFR Outer LED Ring Displays Gasoline values from 11 to 16.75 :1 AFR 0-5V Output Gasoline values from 10 to 20 :1 AFR 0-5V Output E85 values from 6.6 to 13.2 :1 AFR 0-5V Output Ethanol values from 6.14 to 12.3 :1 AFR 0-5V Output Methanol values from 4.4 to 8.8 :1 AFR 0-5V Output Lambda values from .68 to 1.36 Center LED Readout Displays Lambda values from .68 to 1.23 Outer LED Ring Displays Lambda values from .75 to 1.14