Wiring Harnesses | AEM Wideband UEGO AFR Gasoline Failsafe Gauge ; EMS-4 Wiring Harnesses. Patch/Extension Wiring Harnesses. 30 & 20 Amp Relay Wiring Kits. AQ-1 Data Logger Wiring Harnesses. Fuel/Ignition Controller AEM INFORMATION. Warranty/Return. Become a Dealer. Dealer Locator. About AEM Wideband Failsafe Gauge | AEM The Wideband Failsafe Gauge is a Universal Exhaust Gas Oxygen (UEGO—“you-way-go”) controller with an internal boost sensor, an internal data logger and a full color Organic Light Emitting Diode (OLED) display. It includes technology to activate a failsafe strategy in the event AFR falls outside of a user-defined operating window.