How do you change the upstream o2 sensor
the check engine light is on and a mechanic put a machine on it an it detected the upstream o2 sensor
The first generation of the Mazda 6, also known as the Mazda6 and the Mazda Atenza.
Sheila McGriff, the front sensor, located in exhaust manifold, it is accessible from top of engine after first removing the exhaust manifold heat shield. You will need a crow's foot socket (7/8") in order to remove the sensor. They are available at any parts store. Check this video for more instructions. Hope this helps, good luck