Oxygen sensor: Composed of zirconia internal ceramic material, with porous platinum coating and metal shell protection. It improve heat resistance, wear resistance, high temperature resistance and extend the service life of o2 sensors Reference Number: 234-9123: 234 9123, 2349123, 22641-AA36A, 22641 AA36A, 22641AA36A, 22641-AA360, 22641 AA360, 22641AA360 ; 234-4445: 2344445, 22690-AA810, 22690AA810, 22690-AA81A, 22690AA81A, 32010413, 213-2951, 15170, 15172, 24642, OS5331 Compatible Vehicles: Compatible with Subaru Legacy 2.5L 2006-2009 Upstream Downstream; Fit for Subaru FORESTER 2.5L 2005-2010 Upstream Downstream; Subaru IMPREZA 2.5L 2005-2011 Compatible Vehicles: Compatible with Subaru IMPREZA 2.5L 2005-2011 Upstream Downstream; for Subaru OUTBACK 2.5L 2006-2009; for SAAB 9-2X 2.5L 2006 and more Car O2 Sensor Function：O2 sensor monitors the mixed gas, ensuring that the engine is in an optimal combustion state of the mixed gas; The o2 sensor can control the automobile exhaust emission and improve the automobile engine fuel combustion quality 234-9123 234-4445 Upstream Downstream 2Pcs Oxygen Sensor Compatible with Subaru 06-11 Impreza 06-09 Legacy 06-10 Forester 2006-2009 Outback 2006, for Saab 9-2X 2.5L-H4,Replace 22641-AA36A 22690-AA810