Hi Jamie,done a Rav4 a little while ago confused me exhaust at front though big CAT under manifold 4 sensors bank 2 is nearest NO4 cyl,and sensor 1 was before CAT .But on this rav4 sensor 2 was after CAT but on the other side.I found this out by erasing codes and disconnecting each sensor in turn and checking codes.When phoned local Toyota dealer for price of sensors they were at the time about £140 each they said they usually change all four at once bet their customers loved them £560 a time .hope that helps. Martin