The UEGO sensor gives the controller its speed and accuracy. The 4.9 LSU sensor used in the 30 - 4110 AEM Wideband UEGO AFR Controller Gauge has a faster light - off time and draws less current than the 4.2 LSU sensor used with AEM's 30 - 4100 Wideband UEGO Controller Gauge, which will be superseded to the 30 - 4110 gauge in August 2014. The 4.9 LSU sensor features the same fuel compatibility as the 4.2 LSU and NEVER requires free - air calibration when used with AEM's 30 - 4110 Wideband UEGO AFR Gauge. The 30 - 4110's 4.9 LSU sensor uses a different connector than the connector used with the 4.2 LSU sensors included with the original 30 - 4100 gauge controller. The sensors are not interchangeable between the two gauge controllers in any way, including changing connectors on the gauges.