If your Mazda 6's check engine light is on for an O2 sensor, this upstream sensor (Bank 1, Sensor 1) is what you need. Fits 2009 to 2013 Mazda 6 models with the 2.5L L4 engine. It's a 5-wire wideband oxygen sensor that monitors air-fuel ratio for optimal performance and fuel economy. Made with a zirconia element and 310s stainless steel protective sleeve for durability. Features triple sealing technology (rubber seal plus dual laser welding) to prevent exhaust leaks. Wire harness is about 458mm long with a square female connector. Brand new with a 1-year warranty. Replacing a worn upstream sensor can fix issues like rough idle, poor gas mileage, or hesitation. Direct fit – no programming needed. California Prop 65 warning applies. Keep your Mazda running clean and efficient!