P2187 on mazda 3 2006 2.3 L

[gonfire]

Hi, I have a lean engine check engine code on my mazda. The vehicule has 90 000 miles and the 02 sensor has never been changed, so I think this might the cause of the problem. I looked online for a cheap replacement sensor (front, before catalyst?) on this site http://www.autopartswarehouse.com/shop_parts/oxygen_sensor/mazda/3.html

but I dont know witch one to take. Is mine 4 or 3 wire? How can I know this?


Thank's for the help