Bosch Wideband Air/Fuel ratio sensors utilize a sophisticated sensing element that enables them to produce a precise output in proportion to the air/fuel ratio. As a result, a wideband A/F sensor measures exhaust gas oxygen accurately from as rich as 9.0:1 to as lean as free air. Usage of wideband A/F sensors is growing rapidly as original equipment in vehicles and in high-performance specialty markets. Most Emissions products are available for in-store pickup from Advance Auto Parts.