Bank 1 is firewall side (close to driver). Bank 2 is radiator side (close to front bumper).
Bank 1
Bank 2 (radiator side) Upper O2 sensor; Need an O2 sensor removal tool, 7/8 inch or 22 mm crescent wrench.
On this 2-Dimensional picture, ignore the red box and arrow, the Bank 2 Upper is the sensor on the left of the pre-cat (closest to the oil filter). The arrow is pointing to the Bank 2 pre-cat. 1995 OBD I do not have Lower sensors. So, ignore the O2 sensor on the right of the picture.
Originally posted by chongo:
