2Pcs Up & Downstream O2 Oxygen Sensor Fit for: Mazda Miata 1.8L L4 2001-2005 Specifications: OE Numbers: 234-4330, 234-4723, 24087, BP6F18861B9U, Z50118861A9U, Z55318861A9U, BP6G18861C9U,BP8K188619U, 22001, 24684 Product Material: Stainless Steel Product Color: Silver Installation Position: Upstream, Downstream Functions: 1. The Upstream oxygen sensor is used to Monitor Raw Exhaust Gas to Adjust Air-fuel Ratio in Real-time, i.e., it is used to Detect Whether the Exhaust Gas Exceeds the Standard. 2. The Downstream oxygen sensor is mainly used to Detect Whether the Three-way Catalytic Converter Works Normally. .
